A Novel Catalyst Geometry for Automobile Emission Control

The catalytic control of automobile exhaust pollutants (hydrocarbons, carbon monoxide, nitrogen oxides) is now a common practice in the United States and Japan, and there are strong indications that the technology may be introduced in other parts of the world in the coming years. The simultaneous conversion of all three of the above pollutants is achieved by the near-stoichiometric operation of noble metal catalysts which are supported either on alumina particles or on alumina-washcoated cordierite monoliths, A summary of the developments which lead to this technology can be found, e. g., in Hegedus and Gumbleton [1] and references therein.     

13C NMR study of presence of uron structures in amino adhesives and relation with wood‐based panels performance

The chemical structure of amino adhesives produced by the strongly acid process was investigated by ¹³C Nuclear Magnetic Resonance spectroscopy. This technique allowed the identification of functional groups and its quantitative determination. Concentration of cyclic polymeric structures (urons) was shown to be related with adhesive performance and with particleboard physico‐mechanical properties and formaldehyde content. Higher urons concentration presented lower viscosity and reactivity. Particleboards produced with resins with lower urons concentration presented lower formaldehyde content, but also lower internal bond strength. Wood‐based panels produced fulfilled E1 class requirements for formaldehyde emissions, indicating that strongly acid process is an alternative to the conventional alkaline–acid process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4500–4507, 2013     

Selective Oxidation of Glycerol Catalyzed by Rh/Activated Carbon: Importance of Support Surface Chemistry

Abstract  

Noble metal catalysts (Pt, Ir, Pd, Rh, Au) supported on activated carbon were assessed for glycerol oxidation. Rhodium is a highly efficient catalyst when the support has neutral or basic properties. The surface chemistry of activated carbon plays a key role in the performance.     

Understanding the silylation reaction of multi-walled carbon nanotubes

Functional organosilanes were appended, in aprotic and anhydrous conditions, onto multi-walled carbon nanotubes (MWCNTs) previously submitted to three different oxidative treatments: acid, acid with subsequent thermal treatment at 400 °C and 5% O₂/N₂ treatment at 500 °C. The materials were characterised by X-ray photoelectron spectroscopy, elemental analysis, temperature programmed desorption, Fourier transform infrared spectroscopy, thermogravimetry, nitrogen adsorption isotherms at −196 °C and scanning electron microscopy. The techniques provided a correlation between the type and oxygen contents present in the oxidised MWCNTs and the silylation reaction efficiency, leading to a comprehensive overview of the reaction mechanism and materials structure/composition. The highest silylation reaction efficiencies were achieved with the aminosilane in all the oxidised materials and with mercaptosilane in the acid oxidised MWCNTs with nearly 4% Si insertion, whereas for the other organosilanes values lower than 2% were observed. The silylation mechanism was found to proceed through reaction of the alkoxy moieties from the organosilane with phenol surface groups from the MWCNTs; in the case of aminosilane for all MWCNTs and mercaptosilane in acid oxidised MWCNTs, it also occurred by reaction with the carbonyl surface groups. Furthermore, for these latter materials a polymerisation side-reaction was proposed as a parallel functionalisation pathway.     

Electroreductive intramolecular cyclisation of bromoalkoxylated derivatives catalysed by nickel(I) tetramethylcyclam in “green” media

The (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetra-decane)nickel(I), [Ni(tmc)]⁺, electrogenerated at glassy carbon cathodes is shown to be an effective catalyst for the intramolecular radical-type cyclisation of bromoalkoxylated derivatives 1 in alcohol and/or alcohol/water mixtures as well as in microemulsions made with cationic and anionic surfactants. The results obtained indicate that the reaction proceeds via cleavage of the carbon–bromine bond to form a radical-type intermediate that undergoes cyclisation on the unsaturated C–C bond to afford substituted tetrahydrofurans. The reactions are more selective and take place at higher current density than when carried out in conventional aprotic solvents.     

An approach to torque and temperature thread by thread on tapping

During internal threading, small alterations in cutting parameters, tool geometry, or process characteristics produce considerable effects on torque and te     

On the regional incidence of highway investments in the USA

The objective of this paper was to investigate the regional incidence of the aggregate effects of investment in highways in the US taking into consideration the presence of regional spillovers. The empirical results are based on VAR estimates at both the aggregate and state levels using output, employment, and investment, as well as different measures of highway investments. Empirical results allow us to establish several stylized facts. First, investment in highways affects private sector variables positively at the aggregate level as well as in most states. Second, the regional spillover effects are very significant for all private sector variables. Third, these spillovers have a clear geographical pattern in that they tend to be more important in western states and the corridor between the Great Lakes and the Gulf Coast.     

Indoor air quality in Portuguese schools: levels and sources of pollutants

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM_2.5, PM₁₀, bacteria and fungi, carbon dioxide (CO₂), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO₂ and occupancy data. Concentrations of CO₂ exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 μg/m³) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO₂ levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools.     

Effects of simulated deposition of acid mist and iron ore particulate matter on photosynthesis and the generation of oxidative stress in Schinus terebinthifolius Radii and Sophora tomentosa L

Particulate matter is a natural occurrence in the environment, but some industries, such as the iron ore sector, can raise the total amount of particles in the atmosphere. This industry is primarily a source of iron and sulfur dioxide particulates. The effects of the pollutants from the iron ore industries on representatives of restinga vegetation in a Brazilian coastal ecosystem were investigated using physiological and biochemical measures. Two species, Schinus terebinthifolius and Sophora tomentosa, were exposed to simulated deposition of acid mist and iron ore particulate matter in acrylic chambers in a greenhouse. Parameters such as gas exchange, fluorescence emission, chlorophyll content, total iron content, antioxidant enzyme activity and malondialdehyde content were assessed in order to evaluate the responses of the two species. Neither treatment was capable of inducing oxidative stress in S. terebinthifolius. Nevertheless, the deposition of iron ore particulates on this species increased chlorophyll content, the maximum quantum efficiency of photosystem II and the electron transport rate, while iron content was unaltered. On the other hand, S. tomentosa showed a greater sensitivity to the treatments. Plants of S. tomentosa that were exposed to acid mist had a decrease in photosynthesis, while the deposition of iron particulate matter led to an increase in iron content and membrane permeability of the leaves. The activities of antioxidant enzymes, such as catalases and superoxide dismutase, were enhanced by both treatments. The results suggested that the two restinga species use different strategies to overcome the stressful conditions created by the deposition of particulate matter, either solid or wet. It seems that while S. terebinthifolius avoided stress, S. tomentosa used antioxidant enzyme systems to partially neutralize oxidative stress. The findings also point to the potential use of S. tomentosa as a biomarker species under field conditions.     

Okun’s law,asymmetries and regional spillovers: evidence from Virginia metropolitan statistical areas and the District of Columbia

The purpose of this paper was to examine the strength of the relationship between unemployment and GDP, to determine the extent to which this relationship has been stable in Virginia metropolitan statistical areas (MSA) during the Great Recession and to examine the importance of regional spillovers in Okun’s law. Our results suggest that regional spillovers are very important in local labor markets and in defining the relationship observed at the national level. The MSA level data further supports asymmetries in Okun’s law. The weaker direct relationship between GDP and unemployment at the local level suggests that while federal fiscal and monetary policies to stimulate aggregate demand during periods of economic recovery may be effective, over time, in reducing the unemployment rate, local economic development policies are not effective in achieving the substantial short-term reduction in unemployment needed during recovery. The strong business cycle effects observed in the state MSA, relative to the U.S., suggests that countercyclical policies are fundamentally important and should be targeted more generally to exploit regional spillovers.