Bioabsorbable soy protein plastic composites: Effect of polyphosphate fillers on water absorption and mechanical properties

The use of synthetic and natural bioabsorbable plastics has been severely limited due to their low stiffness and strength properties as well as their strong tendency to absorb moisture. This research focused on the development of bioabsorbable polyphosphate filler/soy protein plastic composites with enhanced stiffness, strength, and water resistance. Bioabsorbable polyphosphate fillers, biodegradable soy protein isolate, plasticizer, and adhesion promoter were homogenized and compression-molded. Physical, mechanical, and water absorption testing was performed on the molded specimens. Results showed improvements in stiffness, strength, and water resistance with increasing polyphosphate filler content up to 20% by weight. Application of a coupling agent produced further mechanical property enhancements and a dramatic improvement in water resistance, interpreted by an interfacial chemical bonding model. Examination of the fracture surfaces of the materials revealed that the addition of the polyphosphate fillers changed the failure mode from brittle to pseudo-ductile. These results suggest that these materials are suitable for many load-bearing applications in both humid and dry environments where current soy protein plastics are not usable.     

Environmental justice: A louisiana case study

The paper begins with a brief analysis of the concepts of environmental justice and environmental racism and classism. The authors argue that pollution- and environment-related decision-making is prima facie wrong whenever it results in inequitable treatment of individuals on the basis of race or socio-economic status. The essay next surveys the history of the doctrine of free informed consent and argues that the consent of those affected is necessary for ensuring the fairness of decision-making for siting hazardous facilities. The paper also points out that equal opportunity to environmental protection and free informed consent are important rights. Finally, it presents a case study on the proposed uranium enrichment facility near Homer, Louisiana and argues that siting the plant would violate norms of distributive equity and free informed consent. It concludes that siting the facility is a case of environmental injustice and likely an example of environmental racism or classism.     

STATISTICAL LOW FLOW ESTIMATION USING GIS ANALYSIS IN HUMID MONTANE REGIONS IN PUERTO RICO1

ABSTRACT: Statistical analysis of watershed parameters derived using a Geographical Information system (GIS) was done to develop equations for estimating the 7d–10yr, 30d–10yr, and 7d–2yr low flow for watersheds in humid montane regions of Puerto Rico. Digital elevation models and land use, geology, soils, and stream network coverages were used to evaluate 21 geomorphic, 10 stream channel, 9 relief, 7 geology, 4 climate, and 2 soil parameters for each watershed. To assess which parameters should be used for further investigation, a correlation analysis was used to determine the independence and collinearity among these parameters and their relationship with low flows. Multiple regression analyses using the selected parameters were then performed to develop the statistical models of low flows. The final models were selected in the basis of the Mallow Cp statistic, the adjusted R², the Press statistic, the degree of collinearity, and an analysis of the residuals. In the final models, drainage density, the ratio of length of tributaries to the length of the main channel, the percent of drainage area with northeast aspect, and the average weighted slope of the drainage were the most significant parameters. The final models had adjusted standard errors of 58.7 percent, 59.2 percent, and 48.6 percent for the 7d–10yr, 30d–10yr, and 7d–2yr low flows respectively. For comparison, the best model based on watershed parameters that can be easily measured without a GIS had an adjusted standard error of 82.8 percent.     

Treating contaminated groundwater using a fluidized-bed reactor

Both biological treatment and carbon adsorption have inherent advantages for remediation of groundwater contaminated with compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX). Biological treatment destroys the contaminants and is extremely cost-effective. Carbon adsorption is a positive removal mechanism that ensures a product water of high quality, but the process is relatively expensive and requires frequent carbon replacement and/or regeneration. Coupling the two processes realizes the inherent advantages of both approaches. An additional benefit of combining these removal mechanisms in a biological fluidizedbed reactor (FBR) system is that no loss of BTEX from volatilization occurs, since predissolution of oxygen is used in place of conventional aeration for the fluidized-bed process. This article summarizes preliminary performance data from a laboratory, pilot-scale biological FBR, using granulated activated carbon (GAC) as the support media (GAC-FBR), operated at various BTEX concentrations and organic loading rates. Greater than 99-percent degradation of total BTEX was achieved at an organic loading rate of 3.0 kg COD/m³-day or less and an empty bed hydraulic retention time of 5.0 minutes. System performance was extremely robust, easily handling a tenfold step increase in loading due to the combined adsorptive capability of the biofilm-coated GAC and ability to subsequently bioregenerate the GAC. Monitoring verified that no off-gas was produced during treatment.     

Multi-criteria PSO-based optimal design of grid-connected hybrid renewable energy systems

ABSTRACT

Human-induced climate change through the over liberation of greenhouse gases, resulting in devastating consequences to the environment, is a concern of considerable global significance which has fuelled the diversification to alternative renewable energy sources. The unpredictable nature of renewable resources is an impediment to developing renewable projects. More reliable, effective, and economically feasible renewable energy systems can be established by consolidating various renewable energy sources such as wind and solar into a hybrid system using batteries or back-up units like conventional energy generators or grids. The precise design of these systems is a critical step toward their effective deployment. An optimal sizing strategy was developed based on a heuristic particle swarm optimization (PSO) technique to determine the optimum number and configuration of PV panels, wind turbines, and battery units by minimizing the total system life-cycle cost while maximizing the reliability of the hybrid renewable energy system (HRES) in matching the electricity supply and demand. In addition, by constraining the amount of conventional electricity purchased from the grid, environmental concerns were also considered in the presented method. Various systems with different reliabilities and potential of reducing consumer’s CO₂ emissions were designed and the behavior of the proposed method was comprehensively investigated. An HRES may reduce the annualized cost of energy and carbon footprint significantly.     

Simple protocols to determine dust potentials from cattle feedlot soil and surface samples

Cattle feedlot dust is an annoyance and may be a route for nutrient transport, odor emission, and pathogen dispersion, but important environmental factors that contribute to dust emissions are poorly characterized. A general protocol was devised to test feedlot samples for their ability to produce dust under a variety of environmental conditions. A blender was modified to produce dust from a variety of dried feedlot surface and soil samples and collect airborne particles on glass fiber filters by vacuum collection. A general blending protocol optimized for sample volume (150-175 cm3), blending time (5 min of pre-blending), and dust collection time (15 s) provided consistent dust measurements for all samples tested. The procedure performed well on samples that varied in organic matter content, but was restricted to samples containing less than 200 to 700 g H2O kg(-1) dry matter (DM). When applied to field samples, the technique demonstrated considerable spatial variability between feedlot pen sites. Mechanistically, dust potential was related to moisture and organic matter content. An alternative protocol also demonstrated differences within pen sites in maximum dust potential and dust airborne residence time. The two protocols were not intended, nor are they suitable, for predicting actual particulate matter emissions from agricultural sources. Rather, the protocols rapidly and inexpensively compared the potential for dust emission from samples of differing composition under a variety of environmental conditions.     

The effect of light and heterotrophy on carotenoid concentrations in the Caribbean anemone<Emphasis Type="Italic"> Aiptasia pallida</Emphasis> (Verrill)

One of the consequences of ultraviolet radiation exposure in anthozoans possessing photosynthetic endosymbionts (i.e., zooxanthellae) is production of reactive oxygen species that can damage cellular components, especially lipids and photosynthetic membranes. It is well known that carotenoids are potent antioxidants that can mitigate oxygen radical damage, but the origin of these compounds in zooxanthellate anthozoans is obscured because they can potentially originate from endosymbionts, heterotrophic feeding by the host, or a combination thereof. We used Aiptasia pallida, a common Caribbean anemone, to investigate the effects of exogenous food sources, ultraviolet-A radiation (UVA, 320–400 nm), and photosynthetically active radiation (PAR, 400–700 nm) on carotenoid levels in zooxanthellate anthozoans. Anemones were exposed to one of three simulated light treatments in the laboratory for 38 days: PAR (60% below ambient)/UVA (similar to ambient), PAR/low UVA (42% below ambient), and low PAR (98.4% below ambient)/no UVA. In addition, anemones were either fed a carotenoid-rich diet of Artemia salina nauplii, or starved. Carotenoids identified in A. pallida included peridinin, diadinoxanthin, diatoxanthin and -carotene. While a diet of Ar. salina nauplii had no effect on the carotenoid composition of A. pallida, a two-way analysis of variance revealed that anemones exposed to ambient UVA levels had significantly greater diatoxanthin concentrations relative to the total xanthophyll pool [diato:(diato+diadino)] after 10 days of exposure. This difference among treatments was not present at 20 days, but reappeared as an effect due to starvation rather than UVA at days 30 and 38. These results suggest that carotenoids in A. pallida are not influenced by exogenous feeding and that photoprotective xanthophyll cycling is sensitive to stresses such as UVA and starvation.Communicated by P.W. Sammarco, Chauvin     

Basal area growth of sugar maple in relation to acid deposition,stand health,and soil nutrients

Previous studies have shown in noncalcareous soils that acid deposition may have increased soil leaching of basic cations above the input rate from soil weathering and atmospheric depositions. This phenomenon may have increased soil acidity levels, and, as a consequence, may have reduced the availability of these essential nutrients for forest growth. Fourteen plots of the Forest Ecosystem Research and Monitoring Network in Québec were used to examine the relation between post-industrial growth trends of sugar maple (Acer saccharum Marsh.) and acid deposition (N and S), stand decline rate, and soil exchangeable nutrient concentrations. Atmospheric N and S deposition and soil exchangeable acidity were positively associated with stand decline rate, and negatively with the average tree basal area increment trend. The growth rate reduction reached on average 17% in declining stands compared with healthy ones. The results showed a significant sugar maple growth rate reduction since 1960 on acid soils. The appearance of the forest decline phenomenon in Québec can be attributed, at least partially, to soil acidification and acid deposition levels.