Impact of natural organic matter on monochloramine reduction by granular activated carbon: the role of porosity and electrostatic surface properties

Steady-state monochloramine reduction in fixed-bed reactors (FBRs) was quantified on five types of granular activated carbon (GAC) using two background waters-one natural source water (LAW) containing 2.5-3.5 mg/L organic carbon and one synthetic organic-free water (NW). While more monochloramine was reduced at steady-state using NW compared to LAW for each GAC and empty-bed contact time studied, the differences in removal varied considerably among the GACs tested. Physical characterization of the GACs suggested that the degree of interference caused by natural organic matter (NOM) increased with increasing GAC surface area contained within pores greater than 2 nm in width. Acid/base and electrostatic properties of the GACs were not found to be significant in terms of NOM uptake, which indicated that size exclusion effects of the GAC pores overwhelmed the impact of the GAC surface chemistry. Therefore, selection of GAC to limit the impact of NOM on monochloramine reduction in FBRs should be based on pore size distribution alone, with the impact of NOM decreasing with decreasing mesoporosity and macroporosity.     

Sources of mercury wet deposition in Eastern Ohio, USA

In the fall of 2002, an enhanced air monitoring site was established in Steubenville, Ohio as part of a multi-year comprehensive mercury monitoring and source apportionment study to investigate the impact of local and regional coal combustion sources on atmospheric mercury deposition in the Ohio River Valley. This study deployed advanced monitoring instrumentation, utilized innovative analytical techniques, and applied state-of-the-art statistical receptor models. This paper presents wet deposition data and source apportionment modeling results from daily event precipitation samples collected during the calendar years 2003-2004. The volume-weighted mean mercury concentrations for 2003 and 2004 were 14.0 and 13.5 ng L(-1), respectively, and total annual mercury wet deposition was 13.5 and 19.7 microg m(-2), respectively. Two new EPA-implemented multivariate statistical models, positive matrix factorization (PMF) and Unmix, were applied to the data set and six sources were identified. The dominant contributor to the mercury wet deposition was found by both models to be coal combustion (approximately 70%). Meteorological analysis also indicated that a majority of the mercury deposition found at the Steubenville site was due to local and regional sources.     

Product-oriented flavor research: learnings from the past, visions for the future

In the past flavor research and the development of new flavorings were constantly driven by the interaction of flavor analysis, structure elucidation, and chemical synthesis accompanied by sensory. Highly potent flavor compounds were identified in numerous food products and helped to establish a powerful toolbox for flavorists. Nowadays we experience the merging of various scientific disciplines, for example medicine, biology, chemistry, and various technologies in the field of flavor research, which shows direct impact on our understanding of flavors. At the same time modern life has profoundly changed our eating habits. This situation generates new challenges for product development teams, which represent all facets of technologies. This paper will illustrate different examples for the evolution of product-oriented flavor research and future trends.     

Improved Sanitizing Treatments for Fresh Tomatoes

ABSTRACT:  Fresh tomatoes repeatedly have been associated with major outbreaks of salmonellosis; however, efforts to disinfect them with chlorine or other sanitizing agents have had only mixed success. Our objective was to determine whether hydrogen peroxide (H₂O₂) treatments would be more efficacious than conventional methods in disinfecting tomatoes containing human pathogens and, at the same time, be noninjurious to quality. Tomatoes were dip inoculated with Escherichia coli NRRL B-766 or a Salmonella cocktail and then held for 0, 24, or 48 h at 4 or 24 °C prior to treatment. Treatments included 200 ppm chlorine (Cl₂) at 20 °C for 3 min, water at 20 °C for 3 min or at 60 °C for 2 min, 1% H₂O₂ at 20 °C for 15 min or at 60 °C for 2 min, and 5% H₂O₂ at 60 °C for 2, 3, or 5 min. In tomatoes held 48 h postinoculation, the chlorine treatment was only marginally more effective than an equivalent water rinse in reducing the target bacterial population, while the hot water and 1% H₂O₂ treatments achieved reductions no greater than 1.3 logs. However, application of 5% H₂O₂ at 60 °C resulted in larger reductions. Efficacy of all treatments decreased as the time interval between inoculation and treatment increased. Greater reductions could not be achieved with 5% H₂O₂ at 60 °C by increasing the contact time or addition of surfactants, and these treatments caused some quality loss.     

Validation of a diatom-based index of water quality confirms its utility in monitoring of the Lake Erie's nearshore area

We conducted a validation of the Planktonic Diatom Index (PDI) to demonstrate the utility of a water quality index for the monitoring of Lake Erie's nearshore pelagial zone. Using a large, independent dataset from the Western and Central Basins of Lake Erie for validation ensures realistic assessment of the performance of the index. Diatom-based biomonitoring allows for the inference of integrative information about water quality based on diatom species composition. The PDI is based on the assumption that phosphorus, an established proxy for eutrophication, is instrumental in the structuring of diatom communities. In this study, PDI scores and measured total phosphorus were significantly correlated (r²?=?0.34, r²?=?0.63 outliers removed). However, when samples were considered on a basin-wide basis, the PDI scores were not significantly predicted by measured total phosphorus in the Western Basin. We suggest that snapshot phosphorus measurements are less likely to represent the overall condition in the highly variable, eutrophic Western Basin. When multiple phosphorus measurements were averaged over time, the relationship with the integrative PDI scores was more apparent (r²?=?0.52). Through validation with an independent dataset, we show that the PDI is likely a monitoring tool that provides a robust assessment of water quality in the pelagial zone of the nearshore waters in Lake Erie.     

Application of Motor Control Centers to Systems Having High Available Fault Currents

Rising costs of manufacturing and construction have led to the development of modern distribution systems having higher kVA ratings with larger available fault currents. Because of this, it is essential that special considerations be given to methods that will reduce the available fault current at the motor-control-center incoming terminals to a value that is within the rating of the motor control center.     

Biomimetic hydroxyapatite coating on glass coverslips for the assay of osteoclast activity in vitro

The osteoclast (OC) is the cell type responsible for the resorption of bone. The activity of this cell is important in the aetiology of a large number of skeletal pathologies, and also for the biocompatibility and osseointegration of orthopaedic implant materials. OC mediated acid hydrolysis of calcium phosphate from the bone matrix offers a prime means of studying the biology and activity of this cell type. We have developed a method of coating glass coverslips with a hydroxyapatite (HA)-like mineral, using a biomimetic approach. Hydroxylation followed by formation of a self assembled monolayer (SAM) using the surfactant triethoxysilylpropyl succinic anhydride (TESPSA), allowed biomimetic deposition of HA-like mineral from a simulated body fluid (SBF). The biocompatibility of the TESPSA SAM-HA coated glass coverslips was tested by culturing human mature OC present in samples of giant cell tumour of bone (GCT). Parameters of OC activity were assayed, including F-actin ring formation, release of calcium and formation of osteoclastic resorption pits, confirming that OC were able to attach to and resorb the coated surface. This approach for the preparation of HA coatings on glass coverslips could have wide applicability for the study of osteoclast behaviour in vitro. Gerald J. Atkins and Peter Majewski share senior author status.     

The association between price of regular-grade gasoline and injury and mortality rates among occupants involved in motorcycle- and automobile-related motor vehicle collisions

Motorcyclists have been reported to be more likely to die in a motor vehicle collision (MVC) than automobile occupants. With the recent increase in the pump price of gasoline, it has been reported that people are switching to motorcycles as main modes of transportation. This study evaluated the association between motor vehicle collision-related injury and mortality rates and increases in gasoline prices for occupants of automobiles and riders of motorcycles.There were an estimated 1,270,512 motorcycle MVC and 238,390,853 automobile MVC involved occupants in the U.S. from 1992 to 2007. Higher gasoline prices were associated with increased motorcycle-related injuries and deaths; however, this association no longer remained after accounting for changes in the number of registered vehicles.The current study observed that, while the number of injuries and fatalities in motorcycle-related MVCs increase with increasing gasoline price, rates remained largely unchanged. This suggests that the observed increase in motorcycle-related injuries and fatalities with increasing gasoline price is more a factor of the number of motorcycles on the road rather than operator characteristics.     

Estimation of yellow starthistle abundance through CASI-2 hyperspectral imagery using linear spectral mixture models

The invasive weed yellow starthistle (Centaurea solstitialis) has infested between 4 and 6 million hectares in California. It often forms dense infestations and rapidly depletes soil moisture, preventing the establishment of other species. Precise assessment of its canopy cover, especially low-density abundance in the earlier growing season, is the key to effective management. Compact Airborne Spectrographic Imager 2 (CASI-2) hyperspectral imagery was acquired at the western edge of California's Central Valley grasslands on July 15, 2003. Four linear spectral mixture models (LSMM) were investigated from the original CASI-2 data. Band selections based upon residual analysis and feature extraction (PCA) were further explored to reduce the data dimension. All approaches, except four band-selection unconstrained LSMMs, provide consistent results. The uncertainty of the PCA-based LSMM was estimated through a Monte-Carlo simulation. The maximum standard deviation was approximately 11%. The results suggest that unmixing CASI-2 imagery could be used for estimating and mapping yellow starthistle for larger regional areas.