Catalytic aspects of the steam reforming of hydrocarbons in internal reforming fuel cells

Steam reforming of hydrocarbons such as natural gas is an attractive method of producing the hydrogen fuel gas required by fuel cells. It may be carried out external to the fuel cell or internally. The two types of fuel cell in which internal reforming is most appropriate are the molten carbonate (MCFC), operating at ca. 650°C and the solid oxide (SOFC) which currently operates above 800°C. At such temperatures, the heat liberated by the electrochemical reactions within the cell can be utilised by the endothermic steam reforming reaction. This paper reviews some of the catalytic aspects of internal reforming in these two types of cell. In the MCFC the major catalyst issue is that of long term activity in the presence of a corrosive alkaline environment produced by the cell's electrolyte. In Europe, this is being addressed by British Gas and others, in a programme part-funded by the European Commission. In this programme, potential catalysts for the direct internal reforming MCFC were evaluated in ‘out-of-cell’ tests. This has led to the demonstration of a 1 kW proof-of-concept DIR-MCFC stack and the start of a European ‘Advanced DIR-MCFC’ project. For the SOFC, it has been shown that state-of-the-art nickel cermet anodes can provide sufficient activity for steam reforming without the need for additional catalyst. However, anode degradation may occur when steam reforming is carried out for long periods. New anode materials could therefore offer significant benefits.     

Highly efficient multiphoton-absorption-induced luminescence from gold nanoparticles

We demonstrate that highly efficient photoluminescence is generated from gold nanoparticles as small as a few nanometers in diameter upon irradiation with sub-100-fs pulses of 790-nm light. Strong emission is observed at excitation intensities comparable to or less than those typically used for multiphoton imaging of fluorescently labeled biological samples. The particles have polarized emission, can radiate more efficiently than single molecules, do not exhibit significant blinking, and are photostable under hours of continuous excitation. These observations suggest that metal nanoparticles are a viable alternative to fluorophores or semiconductor nanoparticles for biological labeling and imaging.     

O2 extraction maintains O2 uptake during submaximal exercise with beta-adrenergic blockade at 4,300 m

Whole body O2 uptake (VO2) during maximal and submaximal exercise has been shown to be preserved in the setting of beta-adrenergic blockade at high altitude, despite marked reductions in heart rate during exercise. An increase in stroke volume at high altitude has been suggested as the mechanism that preserves systemic O2 delivery (blood flow x arterial O2 content) and thereby maintains VO2 at sea-level values. To test this hypothesis, we studied the effects of nonselective beta-adrenergic blockade on submaximal exercise performance in 11 normal men (26 +/- 1 yr) at sea level and on arrival and after 21 days at 4,300 m. Six subjects received propranolol (240 mg/day), and five subjects received placebo. At sea level, during submaximal exercise, cardiac output and O2 delivery were significantly lower in propranolol- than in placebo-treated subjects. Increases in stroke volume and O2 extraction were responsible for the maintenance of VO2. At 4,300 m, beta-adrenergic blockade had no significant effect on VO2, ventilation, alveolar PO2, and arterial blood gases during submaximal exercise. Despite increases in stroke volume, cardiac output and thereby O2 delivery were still reduced in propranolol-treated subjects compared with subjects treated with placebo. Further reductions in already low levels of mixed venous O2 saturation were responsible for the maintenance of VO2 on arrival and after 21 days at 4,300 m in propranolol-treated subjects. Despite similar workloads and VO2, propranolol-treated subjects exercised at greater perceived intensity than subjects given placebo at 4,300 m. The values for mixed venous O2 saturation during submaximal exercise in propranolol-treated subjects at 4,300 m approached those reported at simulated altitudes >8,000 m. Thus beta-adrenergic blockade at 4,300 m results in significant reduction in O2 delivery during submaximal exercise due to incomplete compensation by stroke volume for the reduction in exercise heart rate. Total body VO2 is maintained at a constant level by an interaction between mixed venous O2 saturation, the arterial O2-carrying capacity, and hemodynamics during exercise with acute and chronic hypoxia.     

Digital computer program for calculating selectivities of hydrogenation catalysts

Linolenate and linoleate selectivities of hydrogenation catalysts are determined by a digital computer program which solves the kinetic equations of consecutive first-order reactions. The described program is applicable to any initial oil or degree of hydrogenation.     

The interruption of tasks: Methodological, factual, and theoretical issues.

After describing the criterion scores which have been used to assess behavior in the interrupted task paradigm (ITP), a summary of the research literature is presented. ITP as a source of data for evaluating the psychoanalytic theory of repression is found not to allow for the separation of learning and retention effects, and so is not well suited to the study of repression. Similarly, the mediation-avoidance hypothesis makes predictions only concerning interrupted task recall and while it is partially consistent with indirect data, it has yet to receive direct experimental test. The need-achievement conception predicts interrupted task recall satisfactorily but is inapplicable to completed task recall or relative recall scores. ITP is considered as a source of data for a developmental conception of success-failure reactions. Repetition choice scores are found to be consistent with the developmental theory, but some recall results are not. (2-p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinetics of copper-chromite hydrogenation in soybean and linseed oils: Effect of pressure

Although a prime impetus for study of copper catalysts has been the selective reduction of linolenic acid in soybean oil, recent economic developments raise the possibility that hydrogenated linseed oil might be a suitable edible oil. Consequently the effect of two hydrogen pressure levels in soybean and linseed oils on the kinetic pathway and on the final distribution of residual double bonds was investigated. The course of the reaction was studied by removing a sample at intervals corresponding to a small iodine value drop, and constituents were determined analytically. The higher pressure increased the rate of reduction, decreased the concentration of conjugated dienes and somewhat reduced the migration of double bonds. Presented at the AOCS Meeting, Atlantic City, N.J., October 1971. Foreign Research Associate from Lesieur Cotelle Co., Dunkirk, France. N. Market. and Nutr. Res. Div., ARS, USDA.