Sub-ambient cold-start emissions reduction using SwRI® PO x catalyst technology

This paper describes the application of SwRI’s cold-start PO _x catalyst technology to reduce cold-start hydrocarbon emissions from a US Tier 2 vehicle at −7 °C. A reduction in −7 °C (20 °F) cold-start hydrocarbons will help US Tier 2 vehicles meet the proposed EPA NMOG standards. Improvements in cold temperature hydrocarbon emissions would also be beneficial in many parts of Europe during the winter months. In this work, a total hydrocarbon reduction of 19% was realized at 24 °C, in line with previous results, but only up to 3% at −7 °C. Insufficient oxygen in the engine-out exhaust gas at −7 °C was determined to be the reason why the PO _x catalyst failed to significantly reduce HC emissions. Addition of supplemental oxygen to the exhaust during the cold-start, to simulate an adjustment in the engine calibration to less rich operation, resulted in a total hydrocarbon reduction of 18% with the PO _x catalysts in place, but no benefit when the PO _x catalysts were removed. Hence, the PO _x catalyst approach can be used to good effect, even under sub-ambient cold-start conditions.     

Oxidation of Butane to Maleic Anhydride using Vanadium Phosphate Catalysts: Comparison of Operation in Aerobic and Anaerobic Conditions using a Gas-gas Periodic Flow Reactor

The use of a periodic flow reactor is described for the oxidation of butane to maleic anhydride to compare the catalytic performance of vanadium phosphate catalysts operating under aerobic and anaerobic conditions. It is found that for the catalyst prepared via a standard VPO method, operation in the absence of oxygen leads to a very small enhancement in selectivity when butane concentrations in the range 0.9–2.9% are used. Operation in the absence of oxygen leads to very small differences in conversion such that the overall yield is enhanced and this effect is maximised for reactor feeds containing 1.5% butane. However, the enhancement is negligible when the catalyst is operated at high conversion required for commercial operation, indicating that reactors operating with continuous flow with aerobic conditions are preferred. Similar experiments are conducted for a catalyst prepared by the VPD method and, in contrast, this catalyst gives lower butane conversion and maleic anhydride selectivity when operated in the absence of oxygen.     

Density of dilute 3He-4He solutions

The number density of dilute ³He-⁴He solutions under saturated vapor pressure is calculated within the framework of quantum hydrodynamics. For temperatures T small compared to the ³He Fermi temperature T _F, results are given for ³He concentrations large enough to manifest ³He quasiparticle interactions. The nondegenerate regime (TT _F) is also considered in the limit of small ³He concentration. Relevance to experimental determination of quasiparticle energies and interactions is emphasized.Supported by the National Science Foundation under Grant No. GP-40831.     

Adherence to antiretroviral therapy and its impact on clinical outcome in HIV-infected patients.

We analyse data on patient adherence to prescribed regimens and surrogate markers of clinical outcome for 168 human immunodeficiency virus infected patients treated with antiretroviral therapy. Data on patient adherence consisted of dose-timing measurements collected for an average of 12 months per patient via electronic monitoring of bottle opening events. We first discuss how such data can be presented to highlight suboptimal adherence patterns and between-patient differences, before introducing two novel methods by which such data can be statistically modelled. Correlations between adherence and subsequent measures of viral load and CD4+T-cell counts are then evaluated. We show that summary measures of short-term adherence, which incorporate pharmacokinetic and pharmacodynamic data on the monitored regimen, predict suboptimal trends in viral load and CD4+T-cell counts better than measures based on adherence data alone.     

MSC Pretreatment for Improved Transplantation Viability Results in Improved Ventricular Function in Infarcted Hearts

Many clinical studies utilizing MSCs (mesenchymal stem cells, mesenchymal stromal cells, or multipotential stromal cells) are underway in multiple clinical settings; however, the ideal approach to prepare these cells in vitro and to deliver them to injury sites in vivo with maximal effectiveness remains a challenge. Here, pretreating MSCs with agents that block the apoptotic pathways were compared with untreated MSCs. The treatment effects were evaluated in the myocardial infarct setting following direct injection, and physiological parameters were examined at 4 weeks post-infarct in a rat permanent ligation model. The prosurvival treated MSCs were detected in the hearts in greater abundance at 1 week and 4 weeks than the untreated MSCs. The untreated MSCs improved ejection fraction in infarcted hearts from 61% to 77% and the prosurvival treated MSCs further improved ejection fraction to 83% of normal. The untreated MSCs improved fractional shortening in the infarcted heart from 52% to 68%, and the prosurvival treated MSCs further improved fractional shortening to 77% of normal. Further improvements in survival of the MSC dose seems possible. Thus, pretreating MSCs for improved in vivo survival has implications for MSC-based cardiac therapies and in other indications where improved cell survival may improve effectiveness.     

Computer simulation of the corrosion inhibition of copper in acidic solution by alkyl esters of 5-carboxybenzotriazole

A series of alkyl esters (methyl, butyl, hexyl, and octyl) synthesised from a mixture of 4- and 5-carboxybenzotriazole (4-CBTAH and 5-CBTAH) inhibited copper corrosion in aerated solution (pH∼0). Inhibition efficiency (IE%) of the protonated esters (CBTAH₂⁺-R) increased with hydrocarbon chain length and this is attributed to chemisorption (through azole ring N) and increased physical adsorption as more methyl groups are introduced. A modelling package employing molecular mechanics and molecular dynamics has been used to simulate the docking of a single protonated species (5-CBTAH₂⁺-R) onto a clean copper (1 1 0) surface. A decrease in potential energy was associated with the flattening of the ester ring system onto the surface and further decreases in energy were associated with the extension of the aliphatic chain onto the surface. The crude binding energy (E_bind) of each ester with the surface was estimated and this energy also increased regularly with carbon chain length. The study suggests that molecular modelling and calculation of E_bind of a single molecule on a specified metallic surface can be used to predict the inhibition performance of compounds whose structures change in a regular way.     

Light Scattering from Deformed Droplets and Droplets with Inclusions. II. Theoretical Treatment

We provide theoretical results from the scattering of light by deformed liquid droplets and droplets with inclusions. With improved instrumentation and computer technologies available, researchers are able to employ two-dimensional angular optical scattering as a tool for analyzing such particle systems and which then could be applied in industrial, occupational, and military aerosol measurement. We present numerically calculated spatial light-scattering data from various droplet morphologies. We describe characteristic features of the theoretical data and compare these with the experimental results.     

Laboratory investigation of the mass stability of sampling cassettes from inhalable aerosol samplers

A study was conducted to evaluate the mass stability of the materials used in the construction of samplers with internal cassettes for the gravimetric measurement of inhalable aerosol exposures. The internal cassettes from IOM samplers were studied. Results indicate that the mass stability of filters is uniform, but the mass stability of the cassette material may dramatically affect the results of the measurement. Cassettes constructed from plastic exhibited drastic shifts in mass depending on the environmental conditions of their storage. Under room humidity, the plastic cassettes absorbed 1 to 2 mg of water over several days. When these cassettes were placed in a desiccator, they lost mass consistently but did not approach a stable mass. Studies repeated with cassettes made of stainless steel showed negligible mass variability. Based on this study, the use of stainless steel cassettes is recommended for gravimetric determinations of aerosol exposure, although field blanks may in some cases be used for correction of data from plastic cassettes. This study shows the need to evaluate the mass stability of the cassette material of any sampling device where an internal cassette is weighed together with the filter.     

Modulation by ketone bodies of the rate of fatty acid synthesis in mammary gland slices from lactating rats

The absolute rate of fatty acid synthesis was measured in slices of mammary gland from lactating rats by incubation in [³H]₂O-labeled medium containing 10 mM D-3-hydroxybutyrate or aceto-acetate alone and paired in combination with 10 mM glucose, lactate, or pyruvate. When compared with our previous studies, the ketone bodies alone supported significant fatty acid synthesis; the rate of synthesis from either ketone body and lactate was higher than that from pyruvate and lactate, and that from pyruvate and glucose; the rate of synthesis from D-3-hydroxybutyrate and lactate was the highest we have observed in the absence of an exogenous substrate for the hexose monophosphate pathway. This study confirms our previous contention that, in rat mammary gland, substrates formed in the mitochondria can be utilized in the cytosol to provide some of the NADPH necessary for fatty acid synthesis.     

Endotoxic activity of cell-free rumen fluid from cattle fed hay or grain

The cell-free rumen fluid from cattle fed hay or grain exhibited the following biological characteristics which strongly suggest the presence of endotoxin or a toxic principle similar to endotoxin of gram-negative bacteria: proved lethal to mice when injected with actinomycin D; proved extremely lethal to chick embryo; induced biphasic pyogenic response in rabbits; enhanced susceptibility to bacterial infection in mice; evoked positive epinephrine skin reaction in rabbits and phenol-water or aqueous ether proved lethal to mice and chick embryos. A quantitative difference in concentrations of endotoxin was observed on LD50 in mice and chick embryos and response to the epinephrine skin test in rabbits. Cell-free rumen fluid of grain-fed cattle contained at least twice as much endotoxin as that of hay-fed cattle. Endotoxin in cell-free rumen fluid and in higher concentration in cattle fed grain than in those fed hay support the hypothesis that rumen bacterial endotoxins may participate in the pathogenesis of diseases associated with high grain feeding such as lactic acidosis and the sudden-death syndrome.