Quantifying PM2.5 source contributions for the San Joaquin Valley with multivariate receptor models

UNMIX and Positive Matrix Factorization (PMF) solutions to the Chemical Mass Balance (CMB) equations were applied to chemically speciated PM2.5 measurements from 23 sites in California's San Joaquin Valley to estimate source contributions. Six and seven factors were determined by UNMIX for the low_PM2.5 period (February to October) and high_PM2.5 period (November to January), respectively. PMF resolved eightfactors for each period that corresponded with the UNMIX factors in chemical profiles and time series. These factors are attributed to marine sea salt, fugitive dust, agriculture-dairy, cooking, secondary aerosol, motor vehicle, and residential wood combustion (RWC) emissions, with secondary aerosol and RWC accounting for over 70% of PM2.5 mass during the high_PM2.5 period. A zinc factor was only resolved by PMF. The contribution from motor vehicles was between 10 and 25% with higher percentages occurring in summer. The PMF model was further evaluated by examining (1) site-specific residuals between the measured and calculated concentrations, (2) comparability of motor vehicle and RWC factors against source profiles obtained from recent emission tests, (3) edges in bi-plots of key indicator species, and (4) spatiotemporal variations of the factors' strengths. These evaluations support the compliance with model assumptions and give a higher confidence level to source apportionment results for the high_PM2.5 period.     

Feasibility of Including Green Tea Products for an Analytically Verified Dietary Supplement Database

The Dietary Supplement Ingredient Database (DSID) is a federally funded, publicly accessible dietary supplement database that currently contains analytically derived information on micronutrients in selected adult and children's multivitamin and mineral (MVM) supplements. Other constituents in dietary supplement products such as botanicals are also of interest and thus are being considered for inclusion in the DSID. Thirty‐eight constituents, mainly botanicals were identified and prioritized by a federal interagency committee. Green tea was selected from this list as the botanical for expansion of the DSID. This article describes the process for prioritizing dietary ingredients in the DSID. It also discusses the criteria for inclusion of these ingredients, and the approach for selecting and testing products for the green tea pilot study.     

Cr(III) is indirectly oxidized by the Mn(II)-oxidizing bacterium Bacillus sp. strain SG-1

Manganese oxides are the only known oxidants of Cr(III) in the environment, and predictions of the fate of Cr(III) have been based on Cr(III) oxidation rates with well-characterized Mn(III, IV) oxide minerals. Our research, however, indicates that the presence of Mn(II)-oxidizing bacteria may accelerate these rates through the production of very reactive Mn oxides or intermediates formed in the oxidation process. Experiments with the Mn(II)-oxidizing Bacillus sp. strain SG-1 show that this bacterium can accelerate Cr(III) oxidation compared to both abiotic and biologically produced Mn oxides. Initial rates of Cr(III) oxidation by biogenic oxides were approximately 7 times faster than Cr(III) oxidation rates by equivalent amounts of synthetic delta-MnO2 and 25 times faster by SG-1 spores with Mn(II). Cr(III) oxidation by SG-1 is not direct; Mn is required, but only in small amounts, indicating that it is recycled. Cr(III) oxidation is inhibited above 5 microM dissolved Mn(II),while Mn(II) oxidation is not, suggesting that the processes are controlled by different mechanisms. These results illustrate the need to consider bacterial activity and the concentration of Mn when predicting the potential for Cr(III) oxidation.     

Consumer perceptions of novel fruit and familiar fruit: a repertory grid application

To explore how consumers perceive novel and familiar fruit, repertory grid interviews were carried out with 60 New Zealand women. Participants described their perceptions of nine fruit varying in familiarity. The data analysis established a two‐dimensional stimuli space that separated samples with respect to familiarity and the amount of preparation required. Fruit that was familiar was characterised as being well liked, easily available in shops and by a number of different use situations. The primary association with novel fruit was that it was expensive. The participants could not readily think of use situations for fruit they were unfamiliar with. Consumers were separated into groups according to the trait of food neophobia, which pertains to an individual's stable propensity to approach or avoid novel foods. When comparing the most neophobic (n = 14; avoids novel foods) and most neophilic (n = 14; approaches novel foods), individuals perceptual differences were uncovered pertaining to which of the fruit were considered novel and to the suitability of some usage situations (cooking and for children). This finding contributed to the growing evidence of the relationship between food neophobia and consumers' everyday food‐related behaviour. Copyright © 2004 Society of Chemical Industry     

世界水刺产品市场发展情况

近几年来．水刺市场一直围绕纸巾发展。随着纸巾在全球范围内变得越来越普及．非织造布生产商纷纷投资于水刺技术．希望在庞大市场上分得一杯羹。然而，最近．纸巾市场发展趋缓．新生产能力的增加导致了价格竞争。     

In Situ De-esterification of lime pectin

The in situ de-esterification of pectin in lime pulp by the action of pectinesterase (PE) has been investigated. It has been shown that the degree of pectin esterification is reduced to about 20% when the pulp is held at pH 8.5 for 90 min. The rate of de-esterification by the enzyme in situ is highest when the pH is in the range 7.5–9.0 and the NaCl concentration is 0.1–0.3M. At pH values above 9 chemical de-esterification becomes important. The activity of extracted lime PE was shown to be almost independent of pH in the range pH 6.0–9.0. It is suggested that the difference between the behaviour of the extracted and the in situ enzyme is due to the fact that the latter needs to be solubilised before it can act on some of the pectin in the pulp. In support of this it is found that the proportion of lime PE which can be extracted from the pulp decreases with decreasing pH and ionic strength, reflecting electrostatic binding to the cell wall.     

Differentiation of intracellular peptidases of starter and adjunct cultures using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Selection of starter and adjunct cultures is important to minimize bitterness of Cheddar and Gouda cheeses. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry may be useful for rapid screening of cheese cultures for propensity to produce bitter cheese. The objective of this study was to demonstrate the application of MALDI-TOF for differentiating intracellular peptidase activities of starter and adjunct cultures on β-CN f193-209 under simulated cheese condition. Bovine β-casein was incubated with chymosin in 9.55 g/l citrate buffer (pH 5.4, 40 g/l sodium chloride) at 30°C for 24 h, followed by incubation with cell-free extract (CFE) of starter or adjunct culture. Mixed strains of Lactococcus lactis ssp. lactis and L. lactis ssp. cremoris designated as 56 and 105 were the sources of nonbitter and bitter starter cultures, respectively. Lactobacillus helveticus WSU-19 and W900R represented adjunct cultures having high and low debittering activities, respectively. The degradation pattern of β-CN f193-209 by CFE of WSU-19 indicates general aminopeptidase and endopeptidase activities, while degradation of the peptide by CFE of W900R, 56, and 105 are mainly from endopeptidase activity. The rates of β-CN f193-209 hydrolysis by CFE of WSU-19, W900R, 56, and 105 are 6.90, 0.38, 0.39, and 0.23 mg/l per h, respectively.     

Reactivity and mobility of new and old mercury deposition in a boreal forest ecosystem during the first year of the METAALICUS study. Mercury Experiment To Assess Atmospheric Loading In Canada and the US

The METAALICUS (Mercury Experiment To Assess Atmospheric Loading In Canada and the US) project is a whole ecosystem experiment designed to study the activity, mobility, and availability of atmospherically deposited mercury. To investigate the dynamics of mercury newly deposited onto a terrestrial ecosystem, an enriched stable isotope of mercury (202Hg) was sprayed onto a Boreal forest subcatchment in an experiment that allowed us, for the first time, to monitor the fate of 'new' mercury in deposition and to distinguish it from native mercury historically stored in the ecosystem. Newly deposited mercury was more reactive than the native mercury with respect to volatilization and methylation pathways. Mobility through runoff was very low and strongly decreased with time because of a rapid equilibration with the large native pool of "bound" mercury. Over one season, only approximately 8% of the added 212Hg volatilized to the atmosphere and less than 1% appeared in runoff. Within a few months, approximately 66% of the applied 202Hg remained associated with above ground vegetation, with the rest being incorporated into soils. The fraction of 202Hg bound to vegetation was much higher than seen for native Hg (<5% vegetation), suggesting that atmospherically derived mercury enters the soil pool with a time delay, after plants senesce and decompose. The initial mobility of mercury received through small rain events or dry deposition decreased markedly in a relatively short time period, suggesting that mercury levels in terrestrial runoff may respond slowly to changes in mercury deposition rates.