A systematic investigation of carbamate stability constants by 1H NMR

A systematic, experimental investigation into carbamate stability constants using ¹H NMR spectroscopy reveals that both steric hindrance and the acid dissociation constant of the parent amine have a significant effect on the stability of the resulting carbamates. Increasing steric hindrance was found to decrease carbamate stability, while increasing pK of the parent amine was found to increase carbamate stability. The carbamate stability constants of monoethanolamine, propylamine, isobutylamine, 2-amino-1-propanol, aminomethylpropanol and methyldiethanolamine were determined as were the carbamate protonation constants of the first four of these amines.     

Predicting breeding habitat for amphibians: a spatiotemporal analysis across Yellowstone National Park

The ability to predict amphibian breeding across landscapes is important for informing land management decisions and helping biologists better understand and remediate factors contributing to declines in amphibian populations. We built geospatial models of likely breeding habitats for each of four amphibian species that breed in Yellowstone National Park (YNP). We used field data collected in 2000-2002 from 497 sites among 16 basins and predictor variables from geospatial models produced from remotely sensed data (e.g., digital elevation model, complex topographic index, landform data, wetland probability, and vegetative cover). Except for 31 sites in one basin that were surveyed in both 2000 and 2002, all sites were surveyed once. We used polytomous regression to build statistical models for each species of amphibian from (1) field survey site data only, (2) field data combined with data from geospatial models, and (3) data from geospatial models only. Based on measures of receiver operating characteristic (ROC) scores, models of the second type best explained likely breeding habitat because they contained the most information (ROC values ranged from 0.70 to 0.88). However, models of the third type could be applied to the entire YNP landscape and produced maps that could be verified with reserve field data. Accuracy rates for models built for single years were highly variable, ranging from 0.30 to 0.78. Accuracy rates for models built with data combined from multiple years were higher and less variable, ranging from 0.60 to 0.80. Combining results from the geospatial multiyear models yielded maps of "core" breeding areas (areas with high probability values for all three years) surrounded by areas that scored high for only one or two years, providing an estimate of variability among years. Such information can highlight landscape options for amphibian conservation. For example, our models identify alternative areas that could be protected for each species, including 6828-10 764 ha for tiger salamanders, 971-3017 ha for western toads, 4732-16 696 ha for boreal chorus frogs, and 4940-19 690 ha for Columbia spotted frogs.     

Uranium sequestration in sediment at an iron-rich contaminated site at Oak Ridge, Tennessee via. bioreduction followed by reoxidation

This study evaluated uranium sequestration performance in iron-rich(30 g/kg) sediment via bioreduction followed by reoxidation. Field tests(1383 days) at Oak Ridge, Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater. Bioreduction of contaminated sediments(1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L. Aliquots of the bioreduced sediment were reoxidized with O_2, H_2O_2,and NaNO_3, respectively, over 285 days, resulting in aqueous U of 0.024, 1.58 and 14.4 mg/L at pH 6.30, 6.63 and 7.62, respectively. The source-and the three reoxidized sediments showed different desorption and adsorption behaviors of U, but all fit a Freundlich model.The adsorption capacities increased sharply at pH 4.5 to 5.5, plateaued at pH 5.5 to 7.0, then decreased sharply as pH increased from 7.0 to 8.0. The O_2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0. The NO_3~--reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0. The pH-dependent adsorption onto Fe(Ⅲ) oxides and formation of U coated particles and precipitates resulted in U sequestration, and bioreduction followed by reoxidation can enhance the U sequestration in sediment.     

Comparative toxicity of six test chemicals to lettuce using two root elongation test methods

Lettuce (Lactuca sativa L., cv buttercrunch) was used to evaluate and compare the results from two different root elongation phytotoxicity test methods with the same six test substances. Seeds were either germinated in the dark on an inclined filter paper substrate with one end immersed in test solution or germinated in 0.1 strength nutrient solution with a 16 hr light period in a glass bulb mixed and aerated with compressed air. Sodium fluoride, monosodium methanearsonate and monuron reduced lettuce root length at similar concentrations for both methods, while cadmium chloride and 2,4-D root inhibition occurred at concentrations approximately one order of magnitude smaller in the solution culture method than in the substrate method. Two orders of magnitude difference were observed between the two methods for silver nitrate. The results indicate that the solution method is at least as sensitive for all the chemicals tested and much more sensitive for some.     

Latency to resume calling after disturbance in the field cricket,<Emphasis Type="Italic"> Teleogryllus oceanicus</Emphasis>, corresponds to population-level differences in parasitism risk

A possible parasitoid-evasion behavioral adaptation is examined in male field crickets, Teleogryllus oceanicus, from three Hawaiian islands where parasitoid prevalence varies naturally among islands. Ormia ochracea, the parasitoid fly that parasitizes T. oceanicus on these islands, uses male calling song to locate its hosts. We used laboratory-reared males from three Hawaiian islands to determine if there are population differences in the time it takes for calling males to resume calling after a standardized disturbance. Males follow the expected pattern; males from the island with the greatest risk of parasitism have the longest latency to resume calling, and males from the island with the least risk of parasitism have the shortest latency to resume calling. Results are discussed in the context of behavioral adaptations to differing parasitism levels, and trade-offs between natural and sexual selection.Communicated by D. Gwynne     

Municipal solid waste in situ moisture content measurement using an electrical resistance sensor

Moisture content (MC) is a crucial parameter for degradation of solid waste in landfills. Present MC measurement techniques suffer from several drawbacks. A moisture sensor for measurement of in situ moisture content of solid waste in landfills was developed. The sensor measures the electrical resistance across the granular matrix of the sensor, which in turn can be correlated to moisture content. The sensor was also equipped with a thermocouple and tubing that permits simultaneous measurement of temperature and gas sampling. The electrical conductivity of the surrounding moisture and the temperature in the matrix both affect the resistance measurements. This paper describes the results of laboratory experiments designed to select the appropriate granular media particle size, measure the influence of moisture electrical conductivity and temperature, and develop calibration relationships between measured resistance and gravimetrically determined moisture content. With a few limitations, the sensor is able to detect MC of solid waste under conditions allowing moisture movement into the sensor. The application of this technique shows promise for use in bioreactor landfills where high moisture contents are expected and desired.     

COMBINED SEWER OVERFLOW CONTROL THROUGH IN-RECEWING WATER STORAGE: AN EFFICIENCY EVALUATION1

ABSTRACT: A demonstration and efficiency evaluation project was conducted for the flow balancing method (FBM) facility, a combined sewer overflow (CSO) storage facility at Fresh Creek in Brooklyn, New York City. The FBM is a curtained tank located directly in the receiving water that captures CSO. The CSO floats on top of and displaces Fresh Creek saltwater before it is pumped back to the publicly owned treatment works (POTW). The facility was a pilot scale subject to the full CSOs. The purpose of the project was to show how the FBM can withstand severe weather and tidal conditions and to develop a procedure for estimating CSO control efficiency (percentage of CSO pumped back to the POTW). The procedure proved successful and incorporated specific conductivity as a tracer in mass balance equations. These equations provided estimates of the net percent, capture-pumpback of the CSO using the FBM, including the amount of Fresh Creek water that was included in the pumpback to the P01W. The efficiency was directly related to the volume of the CSO and the pumpback rate and ranged from a low of 3.3 percent for the largest event to a high of 76.9 percent for the smallest event. Recent FBM enlargement should result in substantial increases in CSO control. The FBM facility has operated successfully for over five years, withstanding ice storms, near hurricane force winds and up to 7 ft tidal range.     

Labeling Products of Biotechnology: Towards Communication and Consent

Recently, both consumers and producers ofbiotechnology products have insisted thatcommunication between the two be improved. The formerdemand more democratic participation in the riskassessment process of biotechnology products. Thelatter seek to correct misinformation regardingalleged risks from these products. One way to resolvethese concerns, I argue, is through the use ofbiotechnology labels. Such labeling fosters consumerautonomy and moves toward more participatory decisionmaking, in addition to ensuring that informed consentfrom consumers is maintained. Furthermore, althoughvoluntary biotech-free labeling in lieu of biotechlabels may uphold consumer sovereignty, the latterremains a more effective strategy for achievingethical communication between consumers and producersof biotechnology products.     

Retrospective assessment of dryland soil stability in relation to grazing and climate change

Accelerated soil erosion is an aspect of dryland degradation that is affected by repeated intense drought events and land management activities such as commercial livestock grazing. A soil stability index (SSI) that detects the erosion status and susceptibility of a landscape at the pixel level, i.e., stable, erosional, or depositional pixels, was derived from the spectral properties of an archived time series (from 1972 to 1997) of Landsat satellite data of a commercial ranch in northeastern Utah. The SSI was retrospectively validated with contemporary field measures of soil organic matter and erosion status that was surveyed by US federal land management agencies. Catastrophe theory provided the conceptual framework for retrospective assessment of the impact of commercial grazing and soil water availability on the SSI. The overall SSI trend was from an eroding landscape in the early drier 1970s towards stable conditions in the wetter mid-1980s and late 1990s. The landscape catastrophically shifted towards an extreme eroding state that was coincident with the “The Great North American Drought of 1988”. Periods of landscape stability and trajectories toward stability were coincident with extremely wet El Niño events. Commercial grazing had less correlation with soil stability than drought conditions. However, the landscape became more susceptible to erosion events under multiple droughts and grazing. Land managers now have nearly a year warning of El Niño and La Niña events and can adjust their management decisions according to predicted landscape erosion conditions.