Air Quality Dispersion Modelling to Evaluate CIPP Installation Styrene Emissions.

Cured-in-place pipe (CIPP) is one of the most popular in situ rehabilitation techniques to repair sewer and water pipes. While there are multiple approaches to curing CIPP, steam-curing of styrene-based resins has been found to be associated with air-borne chemical emissions. Health officials, utilities and industry representatives have recognized the need to know more about these emissions, especially styrene. Such concern has led to multiple studies investigating the concentrations of volatile organic compounds on CIPP installation sites. This study expands upon previous effort by modeling worst-case, steam-cured CIPP emissions over a 5-year weather record. The effort also includes calibration of the model to emissions averages over the work day rather than instantaneous field measurements. Dispersion modelling software, AERMOD, was utilized to model the styrene component of CIPP emissions on two CIPP installation sites in the US. Based on the analysis results, it was found that the styrene emitted from stacks dissipates rapidly with styrene concentrations only exceeding minimum health and safety threshold levels at distances close to the stack (2 m or less). The values predicted by the model analysis are comparable with the field measured styrene concentrations from other studies. Current safety guidelines in the US recommend a 4.6-m (15-ft) safety perimeter for stack emission points. The results of this study indicate that significant and lasting health impacts are unlikely outside recommended safety perimeter. The results also validate the importance of enforcing recommended safety guidance on steam-cured CIPP sites.

Multichamber Multipotentiostat System for Cellular Microphysiometry.

Multianalyte microphysiometry is a powerful technique for studying cellular metabolic flux in real time. Monitoring several analytes concurrently in a number of individual chambers, however, requires specific instrumentation that is not available commercially in a single, compact, benchtop form at an affordable cost. We developed a multipotentiostat system capable of performing simultaneous amperometric and potentiometric measurements in up to eight individual chambers. The modular design and custom LabVIEW™ control software provide flexibility and allow for expansion and modification to suit different experimental conditions. Superior accuracy is achieved when operating the instrument in a standalone configuration; however, measurements performed in conjunction with a previously developed multianalyte microphysiometer have shown low levels of crosstalk as well. Calibrations and experiments with primary and immortalized cell cultures demonstrate the performance of the instrument and its capabilities.

Feasibility of Energy Dispersive X-Ray Fluorescence Determination of Gold in Soft Tissue for Clinical Applications.

The feasibility of using EDXRF for a rapid quantitative analysis of gold in tumor tissue has been investigated. The protocol described here demonstrates that sample biopsies can be analyzed in as little as 8 hours, with minimal sample preparation. Samples were prepared by drying a 35 µL aliquot of tissue dissolved in KOH in a standard EDXRF cup on a Prolene® support, producing a thin sample. Calibration curves of XRF peak intensity (CPS/mA) to the gold concentration (0-50 PPM) were prepared for liver, tumor, and a mix of tissue types. A linear regression demonstrated an R2 correlation of 0.93. Analysis of experimental samples showed that gold accumulation in tumors (5.8-41.3 PPM) was in agreement with previous studies, where samples were processed using INAA or ICP-MS. This report provides guidance for elemental analysis of gold in tissue in a shorter time span, showing potential for its use in a clinical setting.

Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash.

Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5.00 mg/L, respectively.

Metabolic discrimination of select list agents by monitoring cellular responses in a multianalyte microphysiometer.

Harnessing the potential of cells as complex biosensors promises the potential to create sensitive and selective detectors for discrimination of biodefense agents. Here we present toxin detection and suggest discrimination using cells in a multianalyte microphysiometer (MMP) that is capable of simultaneously measuring flux changes in four extracellular analytes (acidification rate, glucose uptake, oxygen uptake, and lactate production) in real-time. Differential short-term cellular responses were observed between botulinum neurotoxin A and ricin toxin with neuroblastoma cells, alamethicin and anthrax protective antigen with RAW macrophages, and cholera toxin, muscarine, 2,4-dinitro-phenol, and NaF with CHO cells. These results and the post exposure dynamics and metabolic recovery observed in each case suggest the usefulness of cell-based detectors to discriminate between specific analytes and classes of compounds in a complex matrix, and furthermore to make metabolic inferences on the cellular effects of the agents. This may be particularly valuable for classifying unknown toxins.

Real-time cell dynamics with a multianalyte physiometer.

A technique for simultaneously measuring changes in extracellular glucose, lactate, and oxygen concentrations in conjunction with acidification rates on a Cytosensor Microphysiometer is described. Platinum electrodes are inserted into the standard Cytosensor plunger head and modified with enzymes and biocompatible polymeric films. The lactate and glucose oxidase enzymes catalyze the reaction of lactate and glucose. An end product of these catalyses, H2O2, is measured amperometrically. Extracellular oxygen is also measured amperometrically, while the acidification rate is measured potentiometrically by the Cytosensor. Useful information is obtained during the Cytosensor stop-flow cycles, which produce increasing or decreasing peaks, owing to the production of lactic and carbonic acid and consumption of glucose and oxygen by the cells. Fabrication of the modified sensor head and deposition of the electrode films is detailed, and the operation of the technique is described and illustrated by the simultaneous measurement of all four analytes during the addition of 20 mM fluoride to mouse fibro blast cells.

A microphysiometer for simultaneous measurement of changes in extracellular glucose, lactate, oxygen, and acidification rate.

A microphysiometer capable of measuring changes in extracellular glucose, lactate, oxygen, and acidification rate has been developed by incorporating modified electrodes into a standard Cytosensor Microphysiometer plunger. Glucose and lactate are measured indirectly at platinum electrodes by amperometric oxidation of hydrogen peroxide, which is produced from catalysis of glucose and lactate at films containing their respective entrapped oxidase. Oxygen is measured amperometrically at a platinum electrode coated with a Nafion film, while the acidification rate is measured potentiometrically by a Cytosensor Microphysiometer. Analytical information is obtained during the Cytosensor stop-flow cycles, where the electrodes measure changes in the extracellular medium corresponding to the consumption or production of the analyte by the cells. Modification of the Cytosensor plunger for multianalyte determination is described, and the operation of the technique is illustrated by the simultaneous measurement of all four analytes during the addition of fluoride and DNP to Chinese hamster ovary cells and fluoride and antimycin A to mouse fibroblast cells. Cell metabolic recovery and dynamics after exposure to agents can also be observed in specific cases.

Synthesis and catalytic properties of soluble platinum nanoparticles protected by a thiol monolayer.

Several new platinum monolayer protected clusters (MPCs) have been synthesized and characterized. Two methods of platinum reduction were used depending on the solubility of the thiol: sodium borohydride for the water-soluble thiols and lithium triethylborohydride for the organic soluble thiols. In general, reactant solutions containing a 1:1 thiol/Pt ratio yielded the best particles in a single-phase reaction. Higher thiol/Pt ratios produced lower yields of MPCs, while much lower ratios produced gray-black precipitates. The Pt MPCs were used as catalysts to hydrogenate allyl alcohol to propanol by reducing the carbon-carbon double bond. The Pt-mercaptoammonium MPCs were also used as catalysts in the hydrogenation of maleic acid to succinic acid. Differences in the catalytic hydrogenation rates among the various monolayer coatings for MPCs are attributed to the variations in ligand chain length, branching, charged functional groups, packing density, and core size.