Sucrose monolaurate improves the efficacy of sodium hypochlorite against Escherichia coli O157:H7 on spinach

It is well-recognized that chlorine has limited efficacy when applied to inactivate pathogens on fresh produce. One of the many factors limiting efficacy is the high interfacial tension of chlorine-based sanitizers that limits the access of chlorine to the microorganisms. In this work, we investigated the efficacy of sodium hypochlorite (200 ppm, pH 6.0) at 4 and 20 °C against Escherichia coli O157:H7 inoculated on baby spinach leaves as affected by the surfactant sucrose monolaurate (SML) at below (100 ppm), above (250 ppm), and well above (10,000 ppm) the critical micelle concentration (CMC) of ~ 200 ppm at 20 °C. The surfactant-containing chlorine treatments were compared to those with buffer only, surfactant only, and chlorine only. Significantly improved inactivation, as evidenced by survival of E. coli O157:H7 was achieved when 250 or 10,000 ppm SML was added with chlorine. This is attributed to the reduction of interfacial tension between the sanitizing solutions and spinach surface. Treatments at 20 °C resulted in greater mean inactivation than those at 4 °C but the difference was not significant. Comparisons of SML concentrations in treatment solutions before and after sanitization showed that SML decreased more at a lower temperature and when chlorine was present, resulting from adsorption of SML onto spinach matrix. Our work illustrates the importance of using surfactants at concentrations above the CMC to enhance the efficacy of chlorine sanitization.     

Shock tube measurements of species time-histories in monomethyl hydrazine pyrolysis

The first measurements of NH₂ and NH₃ time-histories in monomethyl hydrazine (MMH) pyrolysis were performed behind reflected shock waves in a shock tube using laser absorption techniques. An improved measurement of MMH using IR laser absorption is also presented. MMH concentrations of ∼1% in Ar were employed, over the temperature range 941–1252 K, at pressures near 2 atm. NH₂ was measured at the peak of the overlapping doublet lines at 16739.90 cm⁻¹ (597.4 nm). NH₃ and MMH were measured using direct absorption of CO₂ laser lines at 9.22 and 10.22 μm, respectively. These measurements were then compared to a current comprehensive MMH pyrolysis mechanism based on the work of Sun et al. (2009) and Zhang et al. (2010). Based on the measurements of NH₂ and NH₃, it was possible to measure rate coefficients for two key reactions in the MMH pyrolysis system:(1)CH₃NHNH₂→CH₃NH+NH₂(2)CH₃NHNH₂+NH₂→CH₃NNH₂+NH₃These rates combined with the measured overall MMH decomposition rate strongly imply that Reaction (1) is the dominant MMH decomposition channel. The following rate coefficients (2 atm, 900–1300 K) were uniquely determined:Based on the MMH measurement, the value of the CH₃ decomposition channel is 0–20% of the NH₂ channel, and a value of 1.64 × 10⁵⁸ * T^−12.84 exp(−39580/T) s⁻¹ is recommended for the overall unimolecular decomposition of MMH. Further analysis of the NH₂ measurements indicate that the rate of the following reaction used in the Princeton mechanism should also be significantly increased:(4)CH₃NNH+NH₂→CH₃NN+NH₃The changes to the MMH pyrolysis mechanism recommended in this work result in greatly improved agreement between measured and modeled NH₂, NH₃, and MMH time-histories over the entire range of the study.     

Fat substitutes promote weight gain in rats consuming high-fat diets.

The use of food products designed to mimic the sensory properties of sweet and fat while providing fewer calories has been promoted as a method for reducing food intake and body weight. However, such products may interfere with a learned relationship between the sensory properties of food and the caloric consequences of consuming those foods. In the present experiment, we examined whether use of the fat substitute, olestra, affect energy balance by comparing the effects of consuming high-fat, high-calorie potato chips to the effects of consuming potato chips that sometimes signaled high calories (using high-fat potato chips) and that sometimes signaled lower calories (using nonfat potato chips manufactured with the fat substitute olestra). Food intake, body weight gain and adiposity were greater for rats that consumed both the high-calorie chips and the low-calorie chips with olestra compared to rats that consumed consuming only the high-calorie chips, but only if animals were also consuming a chow diet that was high in fat and calories. However, rats previously exposed to both the high- and low-calorie chips exhibited increased body weight gain, food intake and adiposity when they were subsequently provided with a high fat, high calorie chow diet suggesting that experience with the chips containing olestra affected the ability to predict high calories based on the sensory properties of fat. These results extend the generality of previous findings that interfering with a predictive relationship between sensory properties of foods and calories may contribute to dysregulation of energy balance, overweight and obesity. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Power System Modelling and Fault Analysis of NamPower＇s 330 kV HVAC Transmission Line

Electric power systems usually cover large geographical areas and transmission facilities are continuously increasing. These power systems are exposed to different environmental conditions which may cause faults to occur on the system. Different types of studies are usually done on electric power systems to determine how the system behaves before, during and after a fault condition. The behaviour of variables of interest such as currents, voltage, rotor angle and active and reactive power under fault conditions are studied and observed to help determine possible causes of faults in a power system. The objective of this paper is to investigate a fault that occurred on the 330 kV transmission line between Ruacana power station and Omburu sub-station, the fault caused all the generators at Ruacana power station to trip and consequently caused a blackout at the power station that lasted for 6 h. Preliminary findings showed that the observed fault was an earth fault but the exact type of earth fault was however not known at the time. This research investigation sets out to determine the exact fault that occurred; the most probable cause of the fault, and propose possible solutions to prevent reoccurrence of such a fault. The section of the power network in which the fault occurred was modelled using DigSilent Power Factory software tool, and transient fault analysis was carried out on the model for different fault conditions. Results obtained were then compared with data obtained from NamPower records to ascertain the type of fault.     

Orographic cold-trapping of persistent organic pollutants by vegetation in mountains of western Canada

Conifer needles from mountain areas of Alberta and British Columbia, Canada, were collected from sites that ranged in altitude from 770 to 2200 masl and were analyzed for polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCs) to determine if they are progressively concentrated in colder, more elevated mountain areas, where temperatures decrease as elevation increases. Concentrations of OCs in needles ranged from 43 to 2430 pg g(-1), 55-17500 pg g(-1), and 11-2930 pg g(-1) (dry weight), for total hexachlorocyclohexanes (HCHs), PCBs, and endosulfans, respectively. The more volatile OCs, with subcooled liquid vapor pressures (PL) > 0.1 Pa at 25 degrees C, increased at higher altitudes, whereas the less volatile OCs were either unrelated or inversely correlated with altitude. These spatial patterns were similar for species of spruce (Picea engelmannii and glauca) and pine (Pinus contorta and albicaulis). Back trajectories revealed that air masses arriving at these sites traveled over Asia and the Pacific Ocean before reaching the Rocky Mountains. Results from this study demonstrate that alpine ecosystems accumulate these chemicals to the same degree that is observed in polar environments that are known to receive contaminants by long-range transport.     

Prediction of manure and nutrient excretion from dairy cattle

Accurate estimates of manure excretion are needed for planning manure storage facilities and for nutrient management. Data sets from metabolism studies conducted at several universities were compiled and evaluated for excretion of total manure, N, P, and K. Animal groups included calves weighing up to 204 kg, heifers weighing between 274 and 613 kg, nonlactating cows, and lactating cows. Regression equations were developed to predict excretion of total manure, total dry matter, N, P, and K. Predictors used in the regression equations for lactating cows included milk yield, percentages of protein and fat in milk, dietary concentrations of crude protein and neutral detergent fiber, and intakes of nutrients. The regression equations provide improved predictions of excretion and enable more accurate planning of manure storage and nutrients to be managed at the farm level.     

Treating Seizures after Hypoxic-Ischemic Encephalopathy—Current Controversies and Future Directions

Seizures are common in newborn infants with hypoxic-ischemic encephalopathy and are highly associated with adverse neurodevelopmental outcomes. The impact of seizure activity on the developing brain and the most effective way to manage these seizures remain surprisingly poorly understood, particularly in the era of therapeutic hypothermia. Critically, the extent to which seizures exacerbate brain injury or merely reflect the underlying evolution of injury is unclear. Current anticonvulsants, such as phenobarbital and phenytoin have poor efficacy and preclinical studies suggest that most anticonvulsants are associated with adverse effects on the developing brain. Levetiracetam seems to have less potential neurotoxic effects than other anticonvulsants but may not be more effective. Given that therapeutic hypothermia itself has significant anticonvulsant effects, randomized controlled trials of anticonvulsants combined with therapeutic hypothermia, are required to properly determine the safety and efficacy of these drugs. Small clinical studies suggest that prophylactic phenobarbital administration may improve neurodevelopmental outcomes compared to delayed administration; however, larger high-quality studies are required to confirm this. In conclusion, there is a distinct lack of high-quality evidence for whether and to what extent neonatal seizures exacerbate brain damage after hypoxia-ischemia and how best to manage them in the era of therapeutic hypothermia.     

Xanthophylls, Phytosterols and Pre-β1-HDL are Differentially Affected by Fenofibrate and Niacin HDL-Raising in a Cross-Over Study

Fenofibrate and extended‐release (ER) niacin similarly raise high‐density lipoprotein cholesterol (HDL‐C) concentration but their effects on levels of potent plasma antioxidant xanthophylls (lutein and zeaxanthin) and phytosterols obtained from dietary sources, and any relationship with plasma lipoproteins and pre‐β1‐HDL levels, have not been investigated. We studied these parameters in 66 dyslipidemic patients treated for 6 week with fenofibrate (160 mg/day) or ER‐niacin (0.5 g/day for 3 week, then 1 g/day) in a cross‐over study. Both treatments increased HDL‐C (16 %) and apolipoprotein (apo) A‐I (7 %) but only fenofibrate increased apoA‐II (28 %). Lutein and zeaxanthin levels were unaffected by fenofibrate but inversely correlated with percentage change in apoB and low‐density lipoprotein cholesterol and positively correlated with end of treatment apoA‐II. ApoA‐II in isolated HDL in vitro bound more lutein than apoA‐I. Xanthophylls were increased by ER‐niacin (each ~30 %) without any correlation to lipoprotein or apo levels. Only fenofibrate markedly decreased plasma markers of cholesterol absorption; pre‐β1‐HDL was significantly decreased by fenofibrate (?19 %, p < 0.0001), with little change (3.4 %) for ER‐niacin. Although fenofibrate and ER‐niacin similarly increased plasma HDL‐C and apoA‐I, effects on plasma xanthophylls, phytosterols and pre‐β1‐HDL differed markedly, suggesting differences in intestinal lipidation of HDL. In addition, the in vitro investigations suggest an important role of plasma apoA‐II in xanthophyll metabolism.     

Ozone Generation by Indoor,Electrostatic Air Cleaners

ABSTRACT

This experimental study extends prior studies to consider the influences of discharge polarity, current, relative humidity, air temperature, and wire diameter and material on ozone generation rate in two-stage, wire-plate indoor air cleaners. Promising methods of decreasing the quantity of ozone released into living and work spaces are identified. Use of positive corona discharge is imperative since ozone generation rates are nearly an order of magnitude higher with negative discharge. For a specific precipitator design, the most important parameter in predicting ozone generation rate is current level. Changes in temperature and relative humidity of the inlet air stream over the range of ambient conditions expected in typical homes have less impact. In the commercial air cleaner studied, a 40% reduction in current from 1.08 to 0.60 mA, reduces ozone generation rate by nearly 50% from 0.005 to 0.0025 mg s^?1. This reduction in current reduces particle collection efficiency by 20%. An increase in relative humidity from 17 to 55% decreases ozone generation rate 17%. An increase in air temperature from 293 to 301K decreases ozone generation rate by 6%. Ozone production can be controlled by the selection of wire diameter and material. At a fixed voltage, use of 0.10 mm rather than 0.20 mm tungsten discharge wires reduces ozone generation rate by 40%. The accompanying reduction in current does not cause a reduction in collection efficiency as long as the voltage in the collection stage is held constant. The benefit of controlling ozone generation rate by selection of wire material is that the electrical characteristics of the air cleaner are not affected. With a positive corona discharge, ozone generation rate is decreased by 30% with copper wires and by 50% with silver wires as compared to the rate with standard tungsten wires.     

A Stochastic Model for Particle Deposition and Bounceoff

A new model for particle deposition and bounceoff that combines current knowledge of turbulent bursts with the stochastic properties of turbulent fluctuations is presented. The model predictions for deposition velocities agree with experimental results in the literature for dimensionless particle relaxation time τ_p ⁺ > 2. For τ_p ⁺ > 10, most of the particles delivered to the edge of the viscous sublayer are able to deposit onto the surface due to their inertia; the deposition velocity approaches an asymptotic value because the process becomes limited by the rate of turbulent delivery to the viscous sublayer. Because of the penetration of turbulent fluctuations into the viscous sublayer, the minimum values of vertical velocities needed for particles to deposit onto the surface are smaller than those predicted by the free flight model. Most of the deposition occurs from those turbulent fluctuations at the upper tail of the distribution of the vertical component of air velocity.

In addition to the deposition velocity, the model is able to provide the distribution of particle velocities on reaching the surface which is used to compute the fraction of particle bounceoff. The model predictions for the fractions of rebound agree reasonably with the measured results from a wind tunnel experiment for τ_p ⁺ > 2. However, both the deposition velocity and the fraction of rebound are underestimated by the model for τ_p ⁺ < 2. Other mechanisms such as Brownian diffusion must be included in further revisions to this model in order to obtain satisfactory predictions for smaller values of τ_p ⁺.