The chronology of age-related spatial learning impairment in two rat strains, as tested by the Barnes maze.

The Barnes maze offers advantages for cognitive aging studies, because of its relatively unstressful design and its modest physical demands. The authors therefore undertook a detailed chronological investigation of performance against age, for female Sprague–Dawley and male and female Dark Agouti rats. The trial duration was 10 days. Rats were tested at 6, 11, 14, 17, 20, and 26 months of age, but individual rats were tested at one age only. At 6 months of age, all rats reached the criterion. Sprague–Dawley rats performed best at this age. Impairment began at 14 months in Dark Agouti rats and continued to increase up to 26 months of age. Impairment was greater in Dark Agouti than Sprague–Dawley rats and was greater in females than males. At 26 months, 70% of Sprague–Dawley females reached criterion; of the Dark Agoutis, only 33% of females and 57% of males reached criterion. This study confirms the utility of the Barnes maze as a robust vehicle in aged rats. It also highlights major performance differences between strains and genders in aging rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improved Water Allocation under Limited Water Supplies Using Integrated Soil-Moisture Balance Calculations and Nonlinear Programming

Water allocation under limited water supplies is becoming more important as water becomes scarcer. Optimization models are frequently used to provide decision support to enhance water allocation under limited water supplies. Correct modelling of the underlying soil-moisture balance calculations at the field scale, which governs optimal allocation of water is a necessity for decision-making. Research shows that the mathematical programming formulation of soil-moisture balance calculations presented by Ghahraman and Sepaskhah (2004) may malfunction under limited water supplies. A new model formulation is presented in this research that explicitly models deep percolation and evapotranspiration as a function of soil-moisture content. The new formulation also allows for the explicit modelling of inefficiencies resulting from nonuniform irrigation. Modelling inefficiencies are key to the evaluation of the economic profitability of deficit irrigation. Ignoring increasing efficiencies resulting from deficit irrigation may render deficit irrigation unprofitable. The results show that ignoring increasing efficiencies may overestimate the impact of deficit irrigation on maize yields by a maximum of 2.2 tons per hectare.

     

Comparison of three psychophysical techniques to establish maximum acceptable torques of repetitive ulnar deviation

This study represents a continuation of a series of psychophysical studies on repetitive motions of the wrist and hand conducted at the Liberty Mutual Research Center for Safety and Health. The purpose of this study was to compare maximum acceptable torques of ulnar deviation determined after a replicated training protocol from an earlier single-movement study of ulnar deviation with maximum acceptable torques of ulnar deviation from both the previous single-movement study and two multi-movement studies. A psychophysical methodology was used in which the subject adjusted the resistance on the handle, and the experimenter manipulated or controlled all other variables. After the 1-week training protocol, 14 subjects performed a ulnar deviation task for six 7-hour work days, 2 days at each repetition rate of 15, 20 and 25 motions per minute. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. The subjects recorded symptoms during the last 5 minutes of each hour. By replicating the training protocol of a previous single-movement study, the results of this experiment revealed that maximum acceptable torque of ulnar deviation in this study (1.65Nm or 22% of maximum isometric torque) approached a similar level of torque to that reported in the previous single-movement study for a frequency of 15 per minute. However, when further accommodation was shortened in the 20 and 25 per minute conditions, the acceptable torque levels departed from the previous single-movement study and approached lower levels achieved in the multiple-movement studies which had shorter accommodation times for each movement. These results suggests that the maximum acceptable torque determined through psychophysical methods is dependent upon accommodation time in the protocol and that effect of experimental design (single- vs multi-movement) needs to be further explored.     

Diurnal variation of adrenocortical activity in chronic fatigue syndrome

The nutcracker esophagus, a primary motor disorder, is frequently associated with noncardiac chest pain. However, there are no data on whether its diagnosis, as in other esophageal motility disorders, is delayed. Since the disorder is frequently heralded by alarming symptoms such as chest pain and dysphagia, diagnosis should be made as soon as possible. In this study we assessed the diagnostic delay, if any, in patients with the nutcracker esophagus. Moreover, we were interested in whether the abnormalities described in the distal esophagus could also involve the entire viscus. Fifty-four subjects (age range 23-78 yr) with the nutcracker esophagus were assessed for clinical and manometric variables as an overall group and after dividing them into subgroups according to their symptoms. The manometric variables were compared with those obtained in 61 controls (age range 21-67 yr). Overall, a diagnosis of nutcracker esophagus was made after an average period of 36 +/- 6 months, and surprisingly, this was not different in the various subgroups complaining of either chest pain, dysphagia, or both. Analysis of manometric variables showed that the mean amplitude of contractions was significantly higher in the patients' group at all esophageal body levels, even in the proximal portions. Again, there were no significant differences among the subgroups of nutcracker esophagus with respect to the symptoms. Notwithstanding the presence of alarming symptoms, such as chest pain and dysphagia, the nutcracker esophagus is diagnosed on average after 3 years from the onset of symptoms. Manometric assessment seems to confirm that this entity may indeed represent a primary esophageal motor disorder. The major dysfunction is due to an abnormal increase of contraction amplitude of the entire esophageal body.     

Growth or Survival of Listeria monocytogenes in Ready-to-Eat Meat Products and Combination Deli Salads During Refrigerated Storage

Growth or survival of Listeria monocytogenes in cold‐smoked salmon; sliced, cooked ham; sliced, roasted turkey; shrimp salad; and coleslaw obtained at retail supermarkets stored at 5 °C, 7 °C, or 10 °C (41 °F, 45 °F, or 50 °F, respectively) for up to 14 d was evaluated. Cold‐smoked salmon, ham, and turkey were obtained in case‐ready, vacuum packages. All food products were stored aerobically to reflect additional handling within the retail supermarket. Cold‐smoked salmon, ham, and turkey supported the growth of L. monocytogenes at all 3 storage temperatures. Fitted growth curves of initial populations (about 3 log₁₀ colony‐forming units [CFU]/g) in cold‐smoked salmon, ham, and turkey stored at 5 °C achieved maximal growth rates of 0.29, 0.45, and 0.42 log₁₀ CFU/g growth per day, respectively. Storage at 10 °C increased the estimated maximal growth rate of the pathogen by 0.56 to 1.08 log₁₀ CFU/ g growth per day compared with storage at 5 °C. A decline in populations of L. monocytogenes was observed in shrimp salad and coleslaw, and the rate of decline was influenced by storage temperature. Retention of viability was higher in shrimp salad than in coleslaw, where populations fell 1.2, 1.8, and 2.5 log₁₀ CFU/g at 5 °C, 7 °C, and 10 °C, respectively, after 14 d of storage. Inability of shrimp salad and coleslaw to support the growth of L. monocytogenes may be attributed to the acidic pH (4.8 and 4.5, respectively) of the formulations used in this study. Results show that the behavior of L. monocytogenes in potentially hazardous ready‐to‐eat foods is dependent upon the composition of individual food products as well as storage temperature.     

Antimicrobial properties of the chelating agent EDTA on Streptococcal bovine mastitis isolates

To determine the efficacy of the chelating agent EDTA on microbial growth, separate cultures of two streptococcal bovine mastitis isolates, Streptococcus agalactiae and Streptococcus uberis, were exposed to known concentrations of EDTA. Bacterial cultures of 10(8) CFU/ml were exposed to concentrations of EDTA ranging from 30 to 100 mM in an in-vitro-milk environment. Multiple replications of cultures exposed to EDTA were plated during a two-hour time course. A concentration of 100 mM EDTA resulted in a 90% reduction of S. agalactiae and a 99% reduction of S. uberis. Under these experimental conditions, EDTA treatments in cultures of both isolates exhibited from 1 to 2 log reductions suggesting that EDTA is a potentially effective antimicrobial against streptococcal isolates implicated in causing bovine mastitis.     

Liquid–Liquid Extraction of Butanol from Dilute Aqueous Solutions Using Soybean-Derived Biodiesel

Liquid–liquid extraction (LLE) of mixtures of butanol, 1,3-propanediol (PDO), and ethanol was performed using soybean-derived biodiesel as the extractant. The composition of the mixtures simulated the product of the anaerobic fermentation of biodiesel-derived crude glycerol, which has recently been reported for the first time by the authors. Using a biodiesel: with an aqueous phase volume ratio of 1:1, butanol recovery ranged from 45 to 51% at initial butanol concentrations of 150 and 225 mM, respectively. Less than 10% of the ethanol was extracted, and essentially no PDO was extracted. The partition coefficient for butanol in biodiesel was determined to be 0.91 ± 0.097. This partition coefficient is less than that of oleyl alcohol, which is considered the standard for LLE. However, butanol is suitable for blending with biodiesel, which would eliminate the need for separating the butanol after extraction. Additionally, biodiesel is much less costly than oleyl alcohol. If biodiesel-derived glycerol is used as the feedstock for butanol production, and biodiesel is used as the extractant to recover butanol from the fermentation broth, production of a biodiesel/butanol fuel blend could be a fully integrated process within a biodiesel facility. This process could ultimately help reduce the cost of butanol separation and ultimately help improve the overall economics of butanol fermentation using renewable feedstocks.     

Hurdles and solutions for reactions between gas and liquid in a monolithic reactor

In this paper, proof of principle experiments and exploratory work that solves the problem of ensuring that a gaseous and a liquid reactant are available at the catalytically active site at the same time by separating the reaction and the transport of the gaseous reactant. The equipment consisted of an autoclave in which a feed was saturated with hydrogen, a reactor with a catalyst coated on a monolith, a pump to circulate the feed/product stream, and devices to control and monitor the process.

A lot of information of how the process can be practised was gathered during the work. Conversion per pass should be below the amount of hydrogen that can be dissolved in the liquid to avoid coke deposition (and hence deactivation) of the catalyst. The effectiveness of the catalyst coated on the monolith was found to be 100%.

Several variations of the process design and catalysts used were explored. Integration of the monolith with a heat exchanger will obviously allow for the use of the process for very exothermic reactions like (nitro)benzene hydrogenation. A monolith to which Rh-cyclooctadiene-1,2-bis-diphenylfosfino-ethane (a homogeneous catalyst) was tethered was equally active in hydrogenation of 1-hexene as Rh-cyclooctadiene-1,2-bis-diphenylfosfino-ethane tethered to a standard alumina. This allows (fine)chemical producers to repeatedly use the expensive homogeneous catalysts without the need for separation of the catalyst from the reaction mixture.