Water activity of multicomponent mixture of solutes and non-solutes

An equation has been derived to calculate the water activity (A_w) of multicomponent mixtures of solutes and non‐solutes. The equation is based on a previous Caurie adsorption equation and it depends on the number of component ingredients and the initial moisture contents of the ingredients in the mixture. Solute and non‐solute/water interaction effects in solution were identified as playing important roles in determining accurate equilibrium A_ws of the aqueous mixtures. The new equation allows for interaction effects in mixed solution/suspensions and has been tested on model foods (the data was taken from the literature) containing up to five solutes and non‐solute components. The equation displays a high degree of accuracy. Unlike the Ross equation, which applies only approximately to mixtures of dilute solutions, the new equation applies to mixtures at all solution concentrations and to wet solids.     

Effects of income and urban form on urban NO2: global evidence from satellites

Urban air pollution is among the top 15 causes of death and disease worldwide, and a problem of growing importance with a majority of the global population living in cities. A important question for sustainable development is to what extent urban design can improve or degrade the environment and public health. We investigate relationships between satellite-derived estimates of nitrogen dioxide concentration (NO(2), a key component of urban air pollution) and urban form for 83 cities globally. We find a parsimonious yet powerful relationship (model R(2) = 0.63), using as predictors population, income, urban contiguity, and meteorology. Cities with highly contiguous built-up areas have, on average, lower urban NO(2) concentrations (a one standard deviation increase in contiguity is associated with a 24% decrease in average NO(2) concentration). More-populous cities tend to have worse air quality, but the increase in NO(2) associated with a population increase of 10% may be offset by a moderate increase (4%) in urban contiguity. Urban circularity ("compactness") is not a statistically significant predictor of NO(2) concentration. Although many factors contribute to urban air pollution, our findings suggest that antileapfrogging policies may improve air quality. We find that urban NO(2) levels vary nonlinearly with income (Gross Domestic Product), following an "environmental Kuznets curve"; we estimate that if high-income countries followed urban pollution-per-income trends observed for low-income countries, NO(2) concentrations in high-income cities would be ～10× larger than observed levels.     

EcoWorx, Green Engineering principles in practice

The 12 Principles of Green Engineering have been proposed as a framework within which to examine existing products and guide their redesign as well as to evaluate new product designs. The EcoWorx system represents a recyclable carpet tile product that is assessed using the 12 Principles of Green Engineering and cradle-to-cradle design principles to evaluate environmental, qualitative, and economic performance as compared to existing Shaw carpet tile products. The product design strategy embodies life cycle considerations of a cradle-to-cradle product that puts technical nutrient recovered materials into repeated use. EcoWorx offers a unique opportunity for Shaw to utilize the 12 Principles to analyze and optimize new products and processes for the additional capacity needed to meet rising demand for sustainable carpet products. The analysis of the EcoWorx system demonstrated the value of the 12 Principles in verifying and formalizing the experience and intuition of product designers. This suggests that the mistrial and error reliance on experience could be enhanced with this formalized approach and hence lead to more widespread success of design practices that result in sustainable products.     

Effect of food matrix and cell growth on PCR-based detection of Escherichia coli O157:H7 in ground beef

The purpose of this work was (i) to investigate the feasibility of a previously reported upstream processing method for PCR template preparation to facilitate the detection of Escherichia coli O157:H7 from ground beef and (ii) to assess the impact of cell growth (no growth in the matrix versus growth in the matrix) on molecular detection limits. Two food matrices (autoclaved and raw ground beef) were evaluated in all studies. For no-growth experiments, 10-g meat samples were inoculated with 10(2) to 10(7) CFU/g E. coli O157:H7 and then homogenized. The homogenates were processed to remove large particulates and inhibitors using a two-phase upstream processing method consisting of two sequential centrifugation steps, the second of which used titanous hydroxide to facilitate bacterial immobilization. After upstream processing, sample concentrates were extracted for DNA isolation and amplified by PCR. For growth experiments, 10-g meat samples were inoculated at 1 CFU of E. coli O157:H7 per gram, allowed to grow to 10(2) to 10(7) CFU/g, and then processed for PCR assay. Cell recoveries after upstream processing ranged from 15.9 to 77.6% and were not facilitated by the use of titanous hydroxide, as compared with a saline control (P > 0.05). Bacterial cell recovery and PCR detection limits were similar when comparing autoclaved ground beef and raw ground beef, but cell recoveries were highly variable for raw ground beef samples in which E. coli O157:H7 cells were allowed to grow before processing for detection. Overall, PCR detection limits approximated 10(3) CFU/g of ground beef for all treatments. These results indicate that use of model food systems may not always provide an accurate replication of real-world conditions when evaluating PCR detection limits.     

Development and evaluation of an on-line hide decontamination procedure for use in a commercial beef processing plantt

The hides of cattle are the source of Escherichia coli O157:H7 that contaminates beef carcasses during commercial beef processing. Therefore, effective interventions that reduce hide contamination should reduce subsequent carcass contamination. The first objective of this study was to identify the most effective reagents for decontamination of beef hides. Cattle hides draped over barrels were used for in vitro experiments to compare the efficacy of washes using 1.6% sodium hydroxide, 4% trisodium phosphate, 4% chlorofoam, or 4% phosphoric acid, each followed by a rinse step using either water or acidified (pH 7.0) chlorine at 200 or 500 ppm. All treatments using a water rinse reduced hide coliform counts by 1.5 to 2.5 log CFU/ 100 cm2. Compared with water rinses, 200 and 500 ppm acidified chlorine rinses increased efficacy by approximately 1.0 and 2.0 log CFU/100 cm2, respectively. Vacuuming of the treated areas to remove excess liquid improved hide cleanliness by an average of an additional 1.0 log CFU/100 cm2. The second objective was to evaluate the use of an on-line hide-wash cabinet that used a sodium hydroxide wash and a chlorinated (1 ppm) water rinse. Hides sampled before entering and after exiting the cabinet had aerobic plate counts and Enterobacteriaceae counts that were reduced by 2.1 and 3.4 log CFU/100 cm2, respectively, and the prevalence of E. coli O157 on hides was reduced from 44 to 17% when the cabinet was in use. Preevisceration carcass aerobic plate counts and Enterobacteriaceae counts were both reduced by 0.8 log CFU/100 cm2, and the prevalence of E. coli O157 on preevisceration carcasses was reduced from 17 to 2% when the cabinet was in use. These results support decontamination of hides as an effective means to reduce pathogen contamination of cattle carcasses during processing.     

Comprehensive Review of Patulin Control Methods in Foods

The mycotoxin, patulin (4‐hydroxy‐4H‐furo [3, 2c] pyran‐2[6H]‐one), is produced by a number of fungi common to fruit‐ and vegetable‐based products, most notably apples. Despite patulin's original discovery as an antibiotic, it has come under heavy scrutiny for its potential negative health effects. Studies investigating these health effects have proved inconclusive, but there is little doubt as to the potential danger inherent in the contamination of food products by patulin. The danger posed by patulin necessitates its control and removal from foods products, creating a demand for handling and processing techniques capable of doing so, preferably at low cost to industry. With this being the case, much research has been devoted to understanding the basic chemical and biological nature of patulin, as well as its interaction within foods and food production. While past resarch has elucidated a great deal, patulin contamination continues to be a challenge for athe food industry. Here, we review in depth the past research on patulin with an emphasis upon its influence within the food industry, including its regulation, health effects, biosynthesis, detection, quantification, distribution within foods, and control, during the various stages of apple juice production. Finally, key areas where future patulin research should focus to best control the patulin contamination problem within the food industry are addressed.     

An experimental study of argon condensation in cryogenic shock tubes

Cryogenic shock tubes immersed in liquid nitrogen were used to study condensation onset in argon diluted in helium carrier gas. The condensation in the shock tube expansion fans was detected by light scattering; the pressure was measured and used to calculate temperature, assuming isentropic flow. Previous studies employing supersonic nozzles at higher initial temperatures produced substantial supersaturation at the onset of condensation and agreed well with theory. In contrast, the shock tube experiments showed condensation at states close to equilibrium saturation, having temperatures from 47 to 76 K and pressures from 1 to 166 torr. Possible explanations of the discrepancy require consideration of differences between the two methods in cooling rates and initial temperatures in conjunction with the theory of homogeneous nucleation.     

Effects of Milling Liquid on the Reaction-Bonded Aluminum Oxide Process

The reaction-bonded aluminum oxide process begins with aluminum, Al₂O₃, and usually ZrO₂ powders that have been attrition-milled in an organic liquid. The attrition-milled powder is then compacted and heat-treated in air to produce polycrystalline, Al₂O₃-based ceramics. Safety considerations have made it desirable for the milling liquid to be changed from acetone to a less-flammable solvent. In this paper, mineral spirits, ethanol, and mineral spirits that contains 2 wt% stearic acid are presented as viable alternatives to acetone. The effects of changing the milling liquid on the reaction process and the properties of the final fired ceramic are investigated.