Groundwater contaminated with 1000-2500 µg/L chlorinated ethenes (trichloroethene [TCE], dichloroethene [DCE], vinyl chloride [VC]) was treated by in situ bioaugmentation with a specialized microorganism, Burkholderia cepacia ENV435. The strain was selected for its limited adhesion to aquifer solids and its ability to degrade chlorinated ethenes in the absence of inducing cosubstrates. Approximately 550 L of the toluene ortho-monooxygenaseproducing ENV435 culture (∼100 g/L) was injected along with oxygen (20 mg/L) into a semi-confined silty-sand aquifer (test plot). An equal volume of basal salts medium was simultaneously injected into an adjacent control plot. The plots each measured 4.6 m wide by 12 m long, were spaced 9.2 m apart, and contained 18 multilevel monitoring wells. Groundwater ENV435 concentrations exceeded 1 × 10 8 cfu/mL 7 days after injection, and the strain traveled the 12 m from injection to recovery well with an average linear velocity of 0.37 to 0.54 m/day. By comparison, a bromide tracer passed through the same formation at a rate of 0.53 to 0.68 m/day. In one trial, the total mass of TCE, DCE, and VC in the treated area was reduced by as much as 78% within 2 days after injecting the organisms.

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Vapor extraction (soil venting) has been demonstrated to be a successful and cost‐effective remediation technology for removing VOCs from the vadose (unsaturated) zone. However, in many cases, seasonal water table fluctuations, drawdown associated with pump‐and‐treat remediation techniques, and spills involving dense, non‐aqueous phase liquids (DNAPLS) create contaminated soil below the water table. Vapor extraction alone is not considered to be an optimal remediation technology to address this type of contamination. An innovative approach to saturated zone remediation is the use of sparging (injection) wells to inject a hydrocarbon‐free gaseous medium (typically air) into the saturated zone below the areas of contamination. The contaminants dissolved in the ground water and sorbed onto soil particles partition into the advective air phase, effectively simulating an in situ air‐stripping system. The stripped contaminants are transported in the gas phase to the vadose zone, within the radius of influence of a vapor extraction and vapor treatment system. In situ air sparging is a complex multifluid phase process, which has been applied successfully in Europe since the mid‐1980s. To date, site‐specific pilot tests have been used to design air‐sparging systems. Research is currently underway to develop better engineering design methodologies for the process. Major design parameters to be considered include contaminant type, gas injection pressures and flow rates, site geology, bubble size, injection interval (areal and vertical) and the equipment specifications. Correct design and operation of this technology has been demonstrated to achieve ground water cleanup of VOC contamination to low part‐per‐billion levels.

(1974). British Journal of Industrial Medicine, 31, 10-17. Impairment of nasal mucociliary clearance in woodworkers in the furniture industry. Measurements of mucociliary clearance from the anterior end of the middle turbinate were made using technetium-99m-labelled particles in nine woodworkers from the furniture industry and in 12 controls, none of whom had been occupationally exposed to wood dust. Clearance rates in the controls ranged from 1 9 to 18-5 mm min-' with a mean of 6-8. These values are in good agreement with measurements reported elsewhere for normal subjects. Only one of the woodworkers had a clearance rate which fell within the normal range and he had been occupationally exposed for the shortest period (6 years). In four woodworkers clearance was very slow (< 1 mm min-) and in three there was almost complete stasis. The results of this preliminary investigation suggest that nasal mucociliary function is significantl-y impaired in workers who have been exposed to wood dust in the furniture industry for more than 10 years.

Cognitive fatigue emerges in wide-ranging tasks and domains, but traditional vigilance tasks provide a well-studied context in which to explore the mechanisms underlying it. Though a variety of experimental methodologies have been used to investigate cognitive fatigue in vigilance, relatively little research has utilized electroencephalography (EEG), specifically event-related potentials (ERPs), to explore the nature of cognitive fatigue, also known as the vigilance decrement. Moreover, much of the research that has been done on vigilance and ERPs uses non-traditional vigilance paradigms, limiting generalizability to the established body of behavioral results and corresponding theories. In this study, we address concerns with prior research by (1) investigating the vigilance decrement using a well-established visual vigilance task, (2) utilizing a task designed to attenuate possible confounding ERP components present within a vigilance paradigm, and (3) informing our interpretations with recent findings from ERP research. We averaged data across electrodes located over the frontal, central, and parietal scalp. Then, we generated waveforms locked to the onset of critical low-frequency or non-critical high-frequency events during a 40 min task that was segregated into time blocks for data analysis. There were three primary findings from the analyses of these data. First, mean amplitude of N1 was greater during later blocks for both low-frequency and high-frequency events, a contradictory finding compared to past visual vigilance studies that is further discussed with respect to current interpretations of the N1 in visual attention tasks. Second, P3b mean amplitude following low-frequency events was reduced during later blocks, with a later onset latency. Third and finally, the decrease in P3b amplitude correlated with individual differences in the magnitude of the vigilance decrement, assessed using d′. The results provide evidence for degradations of cognitive processing efficiency brought on by extended time on task, leading to delayed processing and decreased discriminability of critical stimuli from non-critical stimuli. These conclusions are discussed in the context of the vigilance decrement and corresponding theoretical accounts.

We report a method for the rapid and automated measurements of the incorporation kinetics of fluorescent dye-labeled nucleotides by DNA polymerases without using stopped-flow and quench-flow methods. Total internal reflection fluorescence microscopy is used to monitor the incorporation of fluorescently labeled nucleotides by DNA polymerase into surface-bound primed DNA templates, and a microfluidic system is used to perform the reactions. We successfully demonstrated the method using Bst DNA polymerase and a set of coumarin-labeled nucleotides. Our method allows the rapid acquisition of polymerase kinetics for implementing and improving DNA sequencing technologies that rely on labeled nucleotides and DNA polymerases.