Peg Penetration in Three Commercially Important Tasmanian Eucalypt Species

Commercially important species of Tasmanian hardwood timber were immersed in 30% (v/v) polyethylene glycol (PEG) of molecular weights 400, 600, and 1000 and incubated up to seven days at three temperatures (30°C, 45°C, 60°C). Slices obtained from the incubated timber samples were stained with cobalt thiocyanate to indicate the depth of penetration by PEG 400, 600, or 1000 after incubation from two to seven days at the various temperatures. Analysis of the data showed that there was an observable difference in the rate of penetration between each species of eucalypt used in the trial. Incubation time, temperature, and PEG molecular weight were all factors affecting the rate of PEG penetration in a linear fashion and basic density (BD) was the physical property that best supported the trends in this study. This paper is a baseline study that provides the foundation for the quantification and prediction of the movement of PEG into three species of Tasmanian eucalypt timber

Natural Resource Access and Interracial Associations: Black and White Subsistence Fishing in the Mississippi Delta

Using qualitative data gathered over approximately twenty months, we examine how racial divisions between black and white fishers factor into access, harvesting strategies, and use of natural resources in subsistence fishing activities in the Mississippi Delta. Though both races engage in subsistence fishing for many of the same reasons -- a sense of autonomy and economic independence -- clear differences were manifest in their access, harvesting strategies, and utilization of the fish. We document these differences. We conclude that the social relations between white and black subsistence fishers, as they interact with and through the landscape, appear to perpetuate the characteristics of race relations in this region rather than redefine them

Investigation of Pollution in a Karst Aquifer Utilizing Optical Brightener

Optical brightener is an additive to laundry detergents and is found contaminating groundwater. Its concentration may rapidly and inexpensively be determined by fluorescence techniques, and because its source is human wastewater, its presence in groundwater serves as a direct indication of pollution from septic tanks, sewer leaks, and landfills. A total of 105 wells and springs in an area within the Inner Bluegrass Karst Region near Lexington, Kentucky, were described and sampled. Analyses were made for optical brightener (430 samples), total coliform (91), fecal coliform (93), and fecal streptococci (90). As many as 20 optical brightener and 4 bacterial samples were analyzed from a single site during the period from May 20, 1984 to June 17, 1985. Data were also collected on spring discharges, well water.levels, and other site characteristics. Statistical analysis of the relationship between optical brightener and the bacterial indices showed low correlations for both springs and wells, in ·contrast to an earlier study. Although time constraints have precluded a thorough analysis of the data, the difference between the results of the two studies appear to be related to differing site populations and analytic and statistical procedures. The data further suggest that the low correlations between optical brightener and the bacterial indices may be a result of bacterial contamination being largely derived from animal waste and other non-human sources, and that optical brightener may be a more reliable indicator of human contamination

Copper complexation during spring phytoplankton blooms in coastal waters

Cupric ion bioassays were conducted throughout the spring phytoplankton bloom season at two stations-one estuarine, dominated by dinoflagellates, the other coastal, dominated by diatoms. Copper-complexing ligands were detected at both locations throughout this period. Ligand concentrations varied between 0.1 and 0.75 μM, with the estuarine concentrations typically 2–4 times higher than coastal values. Ligands from both locations were destroyed by UV-oxidation and had similar conditional stability constants (range 108.3 to 109.2) that were significantly correlated with pH, suggesting that the complexing materials are organic chelators with weak acid functional groups. All measured or calculated parameters (DOC, ligand concentration, total copper concentration, salinity, and pH) remained relatively constant at the coastal station through time. The estuarine station was more dynamic, with DOC, total copper, and ligand concentrations varying 2–4 fold during the study. Although ligand concentrations were significantly different between the two locations, concomitant fluctuations in total dissolved copper and conditional stability constants resulted in a relatively constant estimate of the maximum free cupric ion activity at both stations (near 10–11 M). This suggests that copper toxicity alone was not responsible for the distinctly different estuarine and nearshore phytoplankton assemblages, although sensitive species might have been inhibited at both locations. Major phytoplankton blooms at both sites were not accompanied by changes in DOC or complexation capacity. A significant inverse correlation between ligand concentration and salinity suggests a terrestrial or sedimentary origin for the copper-complexing compounds

Identifying new lignin bioengineering targets: 1. Monolignol-substitute impacts on lignin formation and cell wall fermentability

<p>Abstract</p> <p>Background</p> <p>Recent discoveries highlighting the metabolic malleability of plant lignification indicate that lignin can be engineered to dramatically alter its composition and properties. Current plant biotechnology efforts are primarily aimed at manipulating the biosynthesis of normal monolignols, but in the future apoplastic targeting of phenolics from other metabolic pathways may provide new approaches for designing lignins that are less inhibitory toward the enzymatic hydrolysis of structural polysaccharides, both with and without biomass pretreatment. To identify promising new avenues for lignin bioengineering, we artificially lignified cell walls from maize cell suspensions with various combinations of normal monolignols (coniferyl and sinapyl alcohols) plus a variety of phenolic monolignol substitutes. Cell walls were then incubated in vitro with anaerobic rumen microflora to assess the potential impact of lignin modifications on the enzymatic degradability of fibrous crops used for ruminant livestock or biofuel production.</p> <p>Results</p> <p>In the absence of anatomical constraints to digestion, lignification with normal monolignols hindered both the rate and extent of cell wall hydrolysis by rumen microflora. Inclusion of methyl caffeate, caffeoylquinic acid, or feruloylquinic acid with monolignols considerably depressed lignin formation and strikingly improved the degradability of cell walls. In contrast, dihydroconiferyl alcohol, guaiacyl glycerol, epicatechin, epigallocatechin, and epigallocatechin gallate readily formed copolymer-lignins with normal monolignols; cell wall degradability was moderately enhanced by greater hydroxylation or 1,2,3-triol functionality. Mono- or diferuloyl esters with various aliphatic or polyol groups readily copolymerized with monolignols, but in some cases they accelerated inactivation of wall-bound peroxidase and reduced lignification; cell wall degradability was influenced by lignin content and the degree of ester group hydroxylation.</p> <p>Conclusion</p> <p>Overall, monolignol substitutes improved the inherent degradability of non-pretreated cell walls by restricting lignification or possibly by reducing lignin hydrophobicity or cross-linking to structural polysaccharides. Furthermore some monolignol substitutes, chiefly readily cleaved bi-phenolic conjugates like epigallocatechin gallate or diferuloyl polyol esters, are expected to greatly boost the enzymatic degradability of cell walls following chemical pretreatment. In ongoing work, we are characterizing the enzymatic saccharification of intact and chemically pretreated cell walls lignified by these and other monolignol substitutes to identify promising genetic engineering targets for improving plant fiber utilization.</p

Double Reflection Dips from Grating Ruled Semiconductors

The Double Reflectivity Dips, Previously Observed by Fischer Et Al. and Anderson Et Al., Which Appeared in the Reflection Spectra of Grating Surfaces On, the Te‐doped Semiconductors GaAs and InSb Around Both the Plasmon and Phonon Frequencies Have Been Measured in More Detail. in the Plasmon Region, Several Possible Explanations of the Phenomenon Are Discussed, But the Favored Explanation Involves Surface Damage. a Simple Two‐region Reflectivity Equation Checked with a Rigorous Grating Theory is Proposed and is Shown to Fit the Data Well. Copyright © 1975 WILEY‐VCH Verlag GmbH & Co. KGa

Commercial users panel

The discussions of motives and requirements for telerobotics application demonstrated that, in many cases, lack of progress was a result not of limited opportunities but of inadequate mechanisms and resources for promoting opportunities. Support for this conclusion came from Telerobotics, Inc., one of the few companies devoted primarily to telerobot systems. They have produced units for such diverse applications as nuclear fusion research, particle accelerators, cryogenics, firefighting, marine biology/undersea systems and nuclear mobile robotics. Mr. Flatau offered evidence that telerobotics research is only rarely supported by the private sector and that it often presents a difficult market. Questions on the mechanisms contained within the NASA technology transfer process for promoting commercial opportunities were fielded by Ray Gilbert and Tom Walters. A few points deserve emphasis: (1) NASA/industry technology transfer occurs in both directions and NASA recognizes the opportunity to learn a great deal from industry in the fields of automation and robotics; (2) promotion of technology transfer projects takes a demand side approach, with requests to industry for specific problem identification. NASA then proposes possible solutions; and (3) comittment ofmotivated and technically qualified people on each end of a technology transfer is essential

Handbook of Field Methods for Monitoring Landbirds

This handbook is a compilation of methods that can be used to assay population size, demographics, and status of many species of birds occurring in a wide variety of habitats. The handbook will prove useful to field biologists, managers, and scientists anywhere in the New World from the arctic through the tropics. The methods include four types of censuses for determining population size and trends, mist-netting and nest searches to determine demographic parameters, and other methods that will be useful in operating a monitoring station, including habitat and weather observations, and suggestions for training personnel and possibilities for detailed studies. Suggestions of specific methods and data forms are included