The positive effect of hydrogen on the reaction of nitric oxide with carbon monoxide over platinum and rhodium catalysts

The effect of adding 330–4930 ppm hydrogen to a reaction mixture of NO and CO (2000 ppm each) over platinum and rhodium catalysts has been investigated at temperatures around 200–250°C. Hydrogen causes large increases in the conversion of NO and, surprisingly, also of CO. Oxygen atoms from the additional NO converted are eventually combined with CO to give CO₂ rather than react with hydrogen to form water. This reaction is described by CO + NO +3/2H₂ CO₂ + NH₃ and accounts for 50–100% of the CO₂ formed with Pt/Al₂O₃ and 20–50% with Rh/Al₂O₃. With the latter catalyst a substantial amount of NO converted produces nitrous oxide. Comparison with a known study of unsupported noble metals suggests that isocyanic acid (HNCO) might be an important intermediate in a reaction system with NO, CO and H₂ present.     

Room temperature CW operation of GaInAsP/InP double heterostructure diode lasers emitting at 1.5 ?m grown by low pressure metalorganic chemical vapour deposition (LP-MO CVD)

Room temperature continuous wave (CW) operation at 1.5 ?m has been achieved in GaInAsP/InP DH lasers fabricated on material grown by low-pressure metalorganic chemical vapour deposition (LP-MO CVD). Threshold currents as low as 200 mA DC have been measured for devices with a stripe width of 9 ?m and a cavity length of 300 ?m. Values of To as high as 64 K have been obtained, where To is defined by the expression Jth(T) = Jth(0) exp (T/To). Fundamental transverse mode oscillation has been achieved up to an output power of 10 mW.     

Anodic behaviour of carbon materials in NaCl saturated NaAlCl4 fused electrolyte at low temperatures: A cyclic voltammetric study

The anodic behaviour of compacted graphite, graphite powder, glassy carbon and reticulated vitreous carbon electrodes in basic sodium chloroaluminate melt in the temperature range 428–573 K was studied using cyclic voltammetry. Chlorine evolution (> + 2.1 V vs Al) alone was the predominant reaction on the compact glassy carbon and fresh RVC electrodes. On compacted graphite, chlorine-assisted chloroaluminate intercalation was found to be a competitive process to the chlorine evolution. At high sweep rates, intercalation/deintercalation near the graphite lattice edges occur faster than chlorine evolution. Subsequent intercalation, however, is a slow process. Chlorine evolution predominates at higher temperatures and at higher anodic potentials. On graphite powders, a more reversible free radical chlorine adsorption/desorption process also occurs in the potential region below chlorine evolution. The process occurs at the grain boundaries, edges and defects of the graphite powder material. Intercalation/deintercalation processes are mainly responsible for the disintegration of graphitic materials in low-temperature chloroaluminate melts. Repeated intercalation/deintercalation cycles result in the irreversible transformation of the electrode surface and electrode characteristics. The surface area of the electrode is increased substantially on cycling. Electrode materials and operating conditions suitable for chlorine generation, intercalation/deintercalation and chlorine adsorption/desorption and power sources based on these processes are identified in this work.     

Kinetics of decarburisation of levitating iron drops by oxygen

This work is focused on determining the rate controlling mechanisms of decarburisation of iron-carbon droplets with gas mixtures containing up to 10% oxygen at 1723 K. The results indicate that the decarburisation rate is limited by the transport of oxygen in the bulk gas to the melt surface. The work also shows the absence of any significant resistance to decarburisation from interfacial chemical kinetics or gas phase reactions. Phosphorus in the melt shows no influence on the rate of decarburisation. Chromium has no significant effect on the decarburisation rate.     

The influence of water on the reduction and reoxidation of ceria

Two different samples of ceria have been characterized by temperature programmed reduction in carbon monoxide (CO-TPR), surface area determination and transmission electron microscopy (TEM). The much higher reducibility at temperatures below 550 °C of a sample prepared by decomposition of cerium carbonate, compared to a commercial ceria, was attributed to the much lower crystallinity. When this ceria, in the partly reduced state, was brought in contact with water vapour, it was readily reoxidised with evolution of hydrogen. The oxygen storage capacity of this sample, determined in cycling experiments, was considerably lowered by the presence of water.     

Btu tax as a revenue option: Its impact on agriculture in the USA

The paper investigates the impact of the imposition of a broadly based energy tax on the US economy in general and the agricultural sectors in particular. The analytical approach used in the analysis consisted of a general equilibrium model composed of 12 producing sectors, 13 consuming sectors, six household categories, classified by income, and the government. The effects of a 10 cents per million Btu tax on energy on prices and quantities are examined. The results are revealing. For example, a 10 cents per million Btu tax on energy imposed at the point of production would result in lower output by the producing sectors (by about $9.154 billion), an increase in the consumption of goods and services (by about $20.292 billion), and a reduction in welfare (by about $4.30 billion). The government would realize an increase in revenue of about $6.356 billion. If the Btu tax were imposed at the point of consumption, there would be lower output by the producing sectors (by about $5.88 billion), an expansion in the consumption of goods and services (by about $19.830 billion), and a reduction in welfare (by about $7.066 billion). The government would realize an increase in revenue of $6.688 billion. The agricultural sectors would be minimally impacted. For example, if a 10 cents per million Btu tax were imposed at the point of production, output in the program crops sector would rise (by $8.3 million), output in the livestock sector would decline (by $83 million), output in the all-other-agriculture-commodities sector would be reduced (by $118 million), and output in the forestry sector would rise (by $34.7 million). If the Btu tax were imposed at the point of consumption, output in the program crops sector would fall (by $38 million), output in the livestock sector would decline (by $42 million), output in the all other agriculture commodities sector would be reduced (by $94 million), and output in the forestry sector would rise (by $221 million).     

Multiresolution Hybrid Mesh for Rapid Prototyping

Stereolithography (STL) is the prevailing technology in rapid prototyping (RP) applications. The STL process involves mesh triangulation of a sculptured object from a CAD model and then the extraction of cross-sections from the mesh model. In most current systems, the resulting model suffers from topological problems, such as degenerate facets, undesired holes, or flipped normals, which lead to invalid cross-sections that cannot be manufactured as layers. This paper proposes a hybrid system that takes advantage of structured and unstructured mesh geometry in order to optimise the RP process and make it more robust and accurate. The system has been developed as part of a joint project between the 3S Laboratory at Grenoble University, France and the Laboratory for Computer Graphics and CAD at the Technion, Israel. Within the system, a constrained mesh simplification model (3S Lab) is integrated with a multilevel model (CAD Lab).     

Timing Nitrogen Fertilizer Application to Reduce Nitrogen Losses to the Environment

The advantage of using insurance to help a farmeradopt a best nitrogen management plan (BNMP) thatreduces the impact of agricultural production on theenvironment is analytically and empiricallydemonstrated. Using an expected value analysis, it isshown that an insurance program can be structured soas to reduce a farmer's cost of bearing the adoptionrisk associated with changing production practicesand, thus, to improve the farmer's certaintyequivalent net return thereby promoting the adoptionof a BNMP. Using the adoption of growing-season onlyN fertilizer application in Iowa as a case study, itis illustrated how insurance may be used to promotethe adoption of this practice to reduce N fertilizeruse. It is shown that it is possible for a farmer andan insurance company both to have an incentive todevelop an insurance adoption program that willbenefit both the farmer and the insurance company,increasing net social welfare and improvingenvironmental quality in Iowa.