Electron spin resonance (ESR) spectroscopic assessment of the contribution of quercetin and other flavonols to the antioxidant capacity of red wines

Health benefits of red wine have been ascribed in part to the antioxidant properties of quercetin and other flavonols. Red wines, however, contain many other polyphenolic compounds with antioxidant potential. The present study has assessed the antioxidant capacity of seven red wines using electron spin resonance spectrometry to measure their ability to donate hydrogen atoms to a stable Fremy's radical. Antioxidant capacity of the wines was strongly related to the total phenol content (r = 0.872, P < 0.01) but less so to total flavonol content (r = 0.651, P < 0.10). The only flavonols detected in the wines by HPLC with post‐column derivatisation were the aglycones and conjugated forms of quercetin and myricetin. These accounted for less than 2% of total phenolic content when expressed as gallic acid equivalents. Although these flavonols showed marked ability to quench Fremy's radical, they contributed less than 1.5% to the total antioxidant capacity of the wines. Consequently, quercetin is not a major antioxidant in red wine. The antioxidant activity of other polyphenols may be of greater importance in contributing to the reputed health benefits of moderate wine consumption. © 1999 Society of Chemical Industry     

Quantum chemical calculations of sulfate adsorption at the Al- and Fe-(hydr)oxide-H20 interface-estimation of gibbs free energies

Quantum chemical calculations were performed to estimate relative Gibbs free energies of sulfate adsorption on variably charged Al- and Fe-(hydr)oxide clusters. Innersphere bidentate bridging and monodentate adsorption were predicted to be exergonic on positively charged Al- and Fe-(hydr)oxides (ranging from -19 to -124 kJ mol-1). However, inner-sphere and H-bonded adsorption on neutral Al- and Fe-(hydr)oxides was predicted to be endergonic (ranging from +5 to +61( kJ mol-1)). Atthe highest positive surface charge, bidentate bridging adsorption was most thermodynamically favorable. At intermediate positive surface charge, bidentate bridging and monodentate adsorption energies were equivalent on Al-(hydr)oxides; monodentate adsorption was more thermodynamically favorable on Fe-(hydr)oxides as compared with bidentate bridging adsorption. The predicted thermodynamic favorability of sulfate adsorption on Al- and Fe-(hydr)oxides was directly related to positive surface charge and indirectly related to the HO-/SO42- exchange stoichiometry, chi. Predicted Gibbs free energies of bidentate bridging and monodentate sulfate adsorption on an Fe-(hydr)oxide cluster (charge = +1, chi = 1) agreed reasonably well with published experimental estimates of sulfate adsorption on geothite (predicted values -34 and -52 kJ mol-1, respectively, and experimental range -36 to -30 kJ mol-').     

Calculation and uses of mean sediment quality guideline quotients: a critical review

Fine-grained sediments contaminated with complex mixtures of organic and inorganic chemical contaminants can be toxic in laboratory tests and/or cause adverse impacts to resident benthic communities. Effects-based, sediment quality guidelines (SQGs) have been developed over the past 20 years to aid in the interpretation of the relationships between chemical contamination and measures of adverse biological effects. Mean sediment quality guideline quotients (mSQGQ) can be calculated by dividing the concentrations of chemicals in sediments by their respective SQGs and calculating the mean of the quotients for the individual chemicals. The resulting index provides a method of accounting for both the presence and the concentrations of multiple chemicals in sediments relative to their effects-based guidelines. Analyses of considerable amounts of data demonstrated that both the incidence and magnitude of toxicity in laboratory tests and the incidence of impairment to benthic communities increases incrementally with increasing mSQGQs. Such concentration/response relationships provide a basis for estimating toxicological risks to sediment-dwelling organisms associated with exposure to contaminated sediments with a known degree of accuracy. This sediment quality assessment tool has been used in numerous surveys and studies since 1994. Nevertheless, mean SQGQs have some important limitations and underlying assumptions that should be understood by sediment quality assessors. This paper provides an overview of the derivation methods and some of the principal advantages, assumptions, and limitations in the use of this sediment assessmenttool. Ideally, mean SQGQs should be included with other measures including results of toxicity tests and benthic community surveys to provide a weight of evidence when assessing the relative quality of contaminated sediments.     

Rough ocean surface and sunglint region characteristics

The sunglint geometrical optics equations of a statistically faceted sea, supported by the so-called interaction probability density and employing an averaging hybrid of the Cox-Munk and Mermelstein slope statistics, was successful in simulating 0.5 microm sunglint region characteristics. The results match independent experimental data, and good agreement is reported for various sea conditions and Sun locations, on sunglint amplitude, sunglint location, and azimuth range. In particular, the peak reflectance shift from the specular direction toward the horizon is correctly predicted, and it is found that the physical mechanism responsible for the shift is the accumulation of contributing facets near the horizon.     

Defining a strategy for chemical imaging of industrial pharmaceutical samples on Raman line-mapping and global illumination instruments

The performance of line-mapping and global illumination Raman systems for two pharmaceutical tablets and a powder blend are assessed in this study. The chemical images were obtained from the placebo, real tablets, and powder blend by using x20, x50, and x100 objectives, as well as via the (pseudo) confocal set-up. The chemical images were produced via univariate wavenumbers and as re-folded principal component (PC) scores (known as score images). In most cases it was easy to image two or three major components of the tablets directly, while the minor components were only imaged via PC scores. The active pharmaceutical ingredients (APIs) were located relatively easily even if present in quite low concentrations (less than 1%) owing to the high Raman scattering coefficients of these materials. The strength of the Raman signal of the API makes it almost ubiquitous in the chemical images of real tablets. Thorough discussion is given on the strategies used to produce chemical images, the prospects of making composite images of all components present in the tablets, and the effects of packing density with relation to the diffusion of the excitation laser light inside the sample. The strengths and weaknesses of the Raman imaging techniques used are emphasized and suggestions are given regarding which instrument is preferable with respect to the goal of the experiment and material under study. For example, mapping technology is preferred for analyzing minor components, while the global illumination approach is recommended for imaging of spatially isolated strong Raman scatterers.     

Synthesis and characterization of stable iron-iron oxide core-shell nanoclusters for environmental applications

Iron-iron oxide core-shell nanoclusters are of great interest due to their potential applications as a remedy for environmental contamination. We report the room-temperature synthesis of core-shell iron-iron oxide nanoclusters using our novel cluster deposition system. Various types of measurements such as Transmission Electron Microscopy, X-ray Diffraction, X-ray Photon Spectroscopy, and Electron Energy Loss Spectroscopy are conducted in characterizing nanoclusters. Stable, monodispersive iron-iron oxide core-shell nanocrystals are identified.     

Interspecies correlation estimates predict protective environmental concentrations

Environmental risk assessments often use multiple single species toxicity test results and species sensitivity distributions (SSDs) to derive a predicted no-effect concentration in the environment, typically the 5th percentile of the SSD, termed the HC5. The shape and location of the distribution are best known when populated with numerous toxicity values. To help overcome the cost of multiple toxicity tests, we explored the potential of the U.S. EPA's Interspecies Correlation Estimation (ICE) program to predict single species toxicity values from a single known toxicity value. ICE uses the initial toxicity estimate for one species to produce correlation toxicity values for multiple species, which can be used to develop SSD and HC5. To test this approach to deriving HC5, we generated toxicity values based on measured toxicity values for three surrogate species Pimephales promelas (Fathead minnow), Onchorynchus mykiss (Rainbow trout), and Daphnia magna (water flea). Algal taxa were not used due to the paucity of high quality algal-aquatic invertebrate and algal-fish correlations. The compounds used (dodecyl linear alkylbenzenesulfonate (LAS), nonylphenol, fenvalerate, atrazine, and copper) have multiple measured toxicity values and diverse modes of action and toxicities. Distribution parameters and HC5 values from the measured toxicity values were compared with ICE predicted distributions and HC5 values. While distributional parameters (scale and intercept) differed between measured and predicted distributions, in general, the ICE-based SSDs had HC5 values that were within an order of magnitude of the measured HC5 values. Examination of species placements within the SSDs indicated that the most sensitive species were coldwater species (e.g., salmonids and Gammarus pseudolimnaeus). These results raise the potential of using quantitative structure activity models to estimate HC5s.     

Aquatic effects of aerial spraying for mosquito control over an urban area

In an effort to combat West Nile Virus, planes dispersed insecticide over Sacramento, CA, treating nearly 50,000 hectares with pyrethrins and the synergist piperonyl butoxide (PBO). Widespread dispersal of insecticide over a metropolitan area, coupled with extensive pretreatment data on the area's urban creeks, provided a unique opportunity to study effects of mosquito control agents on aquatic habitats within an urban setting. There was no evidence of aquatic toxicity from the two active ingredients in the product applied. However, PBO concentrations were high enough to enhance toxicity of pyrethroids already existing in creek sediments from general urban pesticide use. PBO concentrations of 2-4 microg/L were high enough to nearly double the toxicity of sediments to the amphipod Hyalella azteca. Though the increase in toxicity was modest, it was unexpected to find environmental synergy at all. Risk assessments for mosquito control agents have focused on the active ingredients but have failed to recognize the potential for interactions with pesticides previously existing in the environment, which in this case appeared to represent a risk to aquatic life greater than that of the active ingredients themselves.     

Remote sensing of ammonia and sulfur dioxide from on-road light duty vehicles

This study reports the largest data set of on-road, fuel-based mass emissions of ammonia and sulfur dioxide from vehicles of known make, model year, and fuel type. Ammonia is the first pollutant observed for which the emissions decrease with increasing fleet age from 10 to 20 years. The fixed nitrogen emission ratio is 15.0% by mass and 24.7% by mole, larger than current models predict. Diesel fueled vehicles emit more SO2 than gasoline, and unexpectedly, gasoline SO2 emissions decrease continuously with newer model year vehicles.