A Novel Phosphate-Accumulating Bacterium Identified in a Bioreactor for Phosphate Removal from Wastewater

Microbiology - Abstract—Biotechnologies involving phosphate-accumulating organisms, which collect inorganic phosphates from the medium as polyphosphates during cyclic growth under aerobic and...     

Mercury Removal from Air by a Fiber-Based Bioreactor

A partial removal of metallic mercury from air by fiber-based trickle-bed bioreactors was observed. Up to 50 to 65% of the inlet mercury concentrations of 35 to 70 µg/m³ were removed by immobilized live Pseudomonas bacteria for up to 275 hours at a residence time of 1 min. Ninety to 125% of the adsorbed mercury was recovered by a direct assay after dismantling the bioreactors, thus confirming that the observed mercury removal was due to its adsorption by biomass rather than wet scrubbing followed by evaporation. However, mercury removal at a lower inlet concentration (23 µg/m³) was negligible, with a poor material balance. The adsorbed mercury at higher inlet concentrations was not removed from the biomass by a 2-week washing after conclusion of the mercury adsorption experiment, which indicates a strong mercury binding by bacteria. The volatile organic compound removal efficiency was not affected by the presence of up to 70 µg/m³ of metallic mercury in the air.     

A Comparison of Hydrocarbon Vapor Attenuation in the Field with Predictions from Vapor Diffusion Models

This study used field data from three sites in Southern California to evaluate vapor phase transport from: (1) free product (die-sel and gasoline spill) on groundwater; (2) dissolved benzene (gasoline spill) in groundwater; and (3) hydrocarbon-impacted soil (gasoline spill) in the vadose zone. A sampling program to evaluate the vapor pathway included the following: vertical profile data, minimal purging prior to sample collection, field analysis of data, confirmation of field data using a fixed laboratory analysis, and soil physical property data. Comparison of hydrocarbon vapor concentrations measured in this field study with those calculated using vapor diffusion models suggest that an additional attenuation factor of between 500 and 35,000 is needed to account for observed concentrations. Comparison of hydrocarbon profiles with oxygen, carbon dioxide, and methane values is consistent with the interpretation that biodegradation is primarily responsible for the observed attenuation. Therefore, vapor pathway models that do not account for bioattenuation will result in a large overesti-mation of the risk at spill sites and will not be consistent with field data.     

Resistances to the Diffusion of Gas and Vapor in Leaves

Considerable error may be incurred when the component leaf resistances to gases are calculated from the rates of photosynthesis and transpiration measured for the entire leaf. This is due to the fact that there are two parallel pathways for diffusion — through the upper and the lower leaf surfaces — which in most leaves are asymmetrical. True values for the resistances, and predictions of the results of their modification, have been obtained from separate measurements of the photosynthesis and transpiration via the two leaf surfaces.     

Orthonasal and Retronasal Odorant Identification Based upon Vapor Phase Input from Common Substances

Subjects were trained to identify by assigned number commonsubstances presented as vapor phase stimuli via an orthonasalor a retronasal route. Following training, odorant identificationlearning was evaluated by measuring ability to correctly identifyto a criterion. Those who met the criterion were then testedfirst with the stimuli presented to the nares that differedin location from the nares used in training, and second to thenares that corresponded in location to the nares used in training.It was found that, under conditions of natural retronasal breathing,orthonasally trained subjects made correct identifications on{small tilde}80% of the trials upon retronasal testing, butfor the following orthonasal testing identifications were significantlymore frequent, approaching 100% correct. After subsequent retronasaltraining, the same subjects' orthonasal identifications remainedsignificantly higher, although identifications improved to {smalltilde}92% correct on retronasal trials. Other subjects wereinstructed in a breathing technique designed to enhance retronasalstimulation. After orthonasal training, retronasal testing ofthese subjects still gave significantly fewer correct identificationsthan orthonasal testing, notwithstanding the modified retronasalbreathing, but after subsequent retronasal training correctidentifications by these subjects no longer differed significantlybetween orthonasal and retronasal testing. Efficacy of modifiedretronasal breathing was confirmed in two subsequent experiments.The observed substantial positive transfers between retronasaland orthonasal odorant identification training and testing locidemonstrate that these odorant pathways do not subserve completelyindependent olfactory systems, while the less accurate identificationsvia the retronasal route, unless instruction in retronasal breathingwas given, suggest a difference in the efficiency with whichodorants are normally delivered to the olfactory mucosa. Chem.Senses 21: 529–543, 1996.     

A Solution for Removal of Resin from Epoxy Sections

Development of a resin-dissolving solution for use at low alkali concentrations is described. Crown ether dissolved in dimethyl-sulfoxide produces a superbasic alkoxide anion. A five minute treatment resulted in complete resin removal from kidney biopsy specimens embedded in Epon 812. Specimens were well stained by Loeffler's methylene blue. Periodic acid-methenamine silver and Giemsa stains yielded good results. Application of PAS reaction and subsequent hematoxylin counterstaining was practicable for diagnosis.     

Microwave-Assisted Process (MAPTM) for the Extraction of Contaminants from Soil

Laboratory-scale tests were performed to evaluate the use of Environment Canada's patented Microwave-Assisted Process (MAP_TM) for the extraction of petroleum hydrocarbons from contaminated soil. The purpose of these tests was to determine the potential for using the process for large-scale processing of contaminated soil. Tests were performed using three soil types: a certified sediment and certified soil, both contaminated with polycyclic aromatic hydrocarbons (PAHs), and spiked peat soil contaminated with long-chain petroleum hydrocarbons. The test methods used were based on existing MAP techniques that have been proven for the sample preparation of contaminated soils for analytical purposes. The parameters evaluated concentrated on those that are amenable to a continuous large-scale process running at atmospheric pressures. This meant using solvents that are inexpensive and readily available in large volumes, low solvent to material ratios, and optimized energy inputs. In general, it was found that microwaves could be used to enhance the solvent extraction of the contaminants from the soil and that the properties of the soil greatly affected the extent to which the contaminants were removed.     

A Method for the Selective Removal of Deoxyribonucleic Acid from Tissue Sections

The deoxyrihonucleic acid (DNA) of chromatin undergoar depurinization on mild acid hydrolysis with a picric acid-formaldehyde mixture (Bouin's fluid). The apurinic acid thus formed is degraded by condensation with aniline and is lost from tissue sections, but ribonucleic acid (RNA) in nucleoli and cytoplasm is well preserved. Technique: Fi in Carnoy's fluid (ethanol:acetic acid 3:1 or ethanol:chloroform:acetic acid 6:3:1) or in aldehydes (10% formalin or 2.5% glutaraldehyde bsered to pH 7.0). Hydrolyse deparaEnii sections 12-24 hr at 27-50 C in Bouin's fluid, wash in distilled water, immerse in 25% (v/v) acetic acid, treat 1 hr at 27-30 C with 10% (v/v) dine in 25% acetic acid, wash in 25% acetic acid and then in water. Stain 10-40 min with 0₃% toluidine blue in 0.05 M potassium biphthalate bder (pH 4.0); rinse in distilled water, pass to 10% (w/v) ammonium molybdate for 1 min, rinse again in water and pass through tert-butanol and xylene to a synthetic resin. Chromatin and chromosomes are pale green; RNA in nucleoli and cytoplasm deep purple.     

Climate Change,Risks and Contaminants: A Perspective from Studying the Arctic

The Arctic faces threats from climate change and contaminants. Together, these two threats are likely to present surprises centered around the zero-degree isotherm because the phase change of water has enormous potential to affect contaminant transport and transfer, and biological distribution and stress. Particularly at risk are top aquatic predators, migratory species, and species narrowly adapted to ice. These species are most exposed to contaminants, are most likely to become stressed by climate change, or contain within their life cycles efficient vectors of contaminants and diseases. In the Arctic, mercury presents a special case where risks can be altered at many places in the biogeochemical cycle. Atmospheric mercury depletion events offer one such location; however, the methylation of mercury in aquatic systems appears a far more important and presently neglected component of risk from mercury to Arctic ecosystems. Climate variables alter transport, transfer, and capture of contaminants. Therefore, monitoring for contaminants must be conducted with a systems approach that includes climate-related factors. To ensure that the perception of risk is accurate and that priority risks are addressed first, a closer dialogue between scientists, the public, and public administers is urgently required.     

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m²/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.     

Enhanced Microbial Removal of H2S Using Chlorobium in an Optical-Fiber Bioreactor

The removal rate of H₂S in a scratched optical fiber bioreactor using Chlorobium thiosulfatophilum was 0.87 µmol H₂S oxidized·l/min·mg protein, which was 6.7 times that in an external illuminating reactor. Available light intensity with scratched fibers in the bioreactor was 41 µmol/m²·s about 5 times as much as that with unscratched ones.     

Uncertainty in Predicting the Rate of Mass Removal Created by Soil Vapor Extraction Systems

Recently, several soil gas flow and vapor transport numerical models have been developed for use in designing soil vapor extraction (SVE) systems. This article examines how uncertainties in soil properties, specifically permeability, corresponds to uncertainties in the prediction of mass removal rates by numerical models. Scaling equations were first derived for both relevant geometric and nongeometric modeling parameters to enable the examination of the impact of uncertainties associated with spatial variations in soil properties on the prediction of mass removal rates in a somewhat general manner. Monte Carlo analyses of volatile organic compound removal from a hypothetical contaminated soil by SVE were then used to investigate the effect of system operation time and permeability variance on the uncertainty in mass removal rates as predicted by a numerical model. Results showed that uncertainty in the predicted mass removal rate increases as both mass removal increases and as the assumed permeability variance increases. These results indicate that the design of SVE system using deterministic modeling methods may not always correlate to an effective SVE system.     

A Simple and Rapid Method for Standard Preparation of Gas Phase Extract of Cigarette Smoke

Cigarette smoke consists of tar and gas phase: the latter is toxicologically important because it can pass through lung alveolar epithelium to enter the circulation. Here we attempt to establish a standard method for preparation of gas phase extract of cigarette smoke (CSE). CSE was prepared by continuously sucking cigarette smoke through a Cambridge filter to remove tar, followed by bubbling it into phosphate-buffered saline (PBS). An increase in dry weight of the filter was defined as tar weight. Characteristically, concentrations of CSEs were represented as virtual tar concentrations, assuming that tar on the filter was dissolved in PBS. CSEs prepared from smaller numbers of cigarettes (original tar concentrations ≤15 mg/ml) showed similar concentration-response curves for cytotoxicity versus virtual tar concentrations, but with CSEs from larger numbers (tar ≥20 mg/ml), the curves were shifted rightward. Accordingly, the cytotoxic activity was detected in PBS of the second reservoir downstream of the first one with larger numbers of cigarettes. CSEs prepared from various cigarette brands showed comparable concentration-response curves for cytotoxicity. Two types of CSEs prepared by continuous and puff smoking protocols were similar regarding concentration-response curves for cytotoxicity, pharmacology of their cytotoxicity, and concentrations of cytotoxic compounds. These data show that concentrations of CSEs expressed by virtual tar concentrations can be a reference value to normalize their cytotoxicity, irrespective of numbers of combusted cigarettes, cigarette brands and smoking protocols, if original tar concentrations are ≤15 mg/ml.     

Twenty Years of Gas Phase Structural Biology

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Adsorption of the Vapor Phase Components in Cigarette Smoke by Activated Carbon in Vented Filters

Using vented charcoal filters, the adsorption efficiencies of acetaldehyde, isoprene and acetone, the major components in the vapor phase of cigarette smoke, were studied. Filter ventilation was found to raise the adsorption efficiency of the adsorbent. The effect of increasing the ventilation rate through the filter was greatest for the adsorption of acetaldehyde. In order to clarify the effects of decreases of the flow rate and the concentration caused by ventilation, the adsorption by unvented charcoal filters under varied conditions was also measured. Although both raised the adsorptions of the three components, the lowered concentration was contributed to mainly by an increase of adsorption by the vented charcoal filters. Regardless of whether the filter was perforated or not, the adsorptions of the three components depended on the volume of the air drawn in at the top of the lighted end of the cigarette.