Numerical simulation of horizontal jet penetration in a three-dimensional fluidized bed

The introduction of reactant gas as a jet into a fluidized bed chemical reactor is often encountered in various industrial applications. Understanding the hydrodynamics of the gas and solid flow resulting from the gas jet can have considerable significance in improving the reactor design and process optimization. In this work, a three-dimensional numerical simulation of a single horizontal gas jet into a cylindrical gas-solid fluidized bed of laboratory scale is conducted. A scaled drag model is proposed and implemented into the simulation of a fluidized bed of FCC particles. The gas and particles flow in the fluidized bed is investigated by analyzing the transient simulation results. The jet penetration lengths of different jet velocities have been obtained and compared with published experimental data as well as with predictions of empirical correlations. The predictions by several empirical correlations are discussed. A good agreement between the numerical simulation and experimental results has been achieved.     

Characterizations and photocatalytic activity comparisons of N-doped nc-TiO2 depending on synthetic conditions and structural differences of amine sources

N-doped TiO₂ nanoparticles were prepared by using 1° and 2° alkyl and alcohol amines [n-propylamine (nPRYL), ethanolamine (ETOH), propanolamine (PROH), diethylamine (DETYL), dipropylamine (DPRYL), diethanolamine (DETOH), and ammonium hydroxide (NH₄OH)] as nitrogen sources through microwave and hydrothermal growth (HT) methods. Characterization of the nanoparticles was done by X-ray diffraction, scanning electron microscopy, ultraviolet-visible absorption spectra, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and BET analysis techniques. Nitrogen species in TiO₂ lattice were interstitial impurities. Nitrogen content of the particles depended on the preparation conditions and structural differences of nitrogen sources. Photocatalytic degradation of methylene blue was carried out under Xenon lamp irradiation. N-doped TiO₂ nanoparticles exhibited higher photocatalytic activity, compared to undoped ones. Acidity differences of amine sources and irradiation differences of synthetic conditions had an effect on photocatalytic activity. Although N doping into TiO₂ lattice was the least effective in the particle prepared by the use of nPRYL as the amine source and HT as the synthetic condition, its photocatalytic activity was slightly better compared to others.     

Using river distance and existing hydrography data can improve the geostatistical estimation of fish tissue mercury at unsampled locations

Mercury in fish tissue is a major human health concern. Consumption of mercury-contaminated fish poses risks to the general population, including potentially serious developmental defects and neurological damage in young children. Therefore, it is important to accurately identify areas that have the potential for high levels of bioaccumulated mercury. However, due to time and resource constraints, it is difficult to adequately assess fish tissue mercury on a basin wide scale. We hypothesized that, given the nature of fish movement along streams, an analytical approach that takes into account distance traveled along these streams would improve the estimation accuracy for fish tissue mercury in unsampled streams. Therefore, we used a river-based Bayesian Maximum Entropy framework (river-BME) for modern space/time geostatistics to estimate fish tissue mercury at unsampled locations in the Cape Fear and Lumber Basins in eastern North Carolina. We also compared the space/time geostatistical estimation using river-BME to the more traditional Euclidean-based BME approach, with and without the inclusion of a secondary variable. Results showed that this river-based approach reduced the estimation error of fish tissue mercury by more than 13% and that the median estimate of fish tissue mercury exceeded the EPA action level of 0.3 ppm in more than 90% of river miles for the study domain.     

Long-term evaluation of the fate of sulfur mustard on dry and humid soils, asphalt, and concrete

The long-term fate of the blister agent sulfur mustard (HD, bis(2-chloroethyl)sulfide) was determined in a variety of commercial and natural matrices. HD was found to be extremely stable in dry matrices for over a year. The addition of 5% water to the matrices induced slow degradation of HD, which lasted several months. The major degradation product in sands and asphalt was found to be a sulfonium salt, S[CH(2)CH(2)S(+)(CH(2)CH(2)OH)(2)](2) (H-2TG). Red loam soil, which has not been examined before, exhibited strong interaction with HD, both in dry form and in the presence of water. Humid red loam soil gave rise to unique oxidative degradation products. On humid concrete HD degraded to a complex mixture of products, including vinyls. This may be attributed to the basic sites incorporated in concrete.     

Development of a method to assess cigarette smoke intake

Tar and nicotine deliveries of cigarettes measured using current standardized smoking machine protocols provide poor estimates of smoke exposure. The characteristics of human smoking behavior vary considerably and differ from the rigid parameters used with current standardized smoking machine protocols. Current alternatives, including measurement of biomarkers, are invasive, time-dependent, and can be too expensive to be used as mechanisms for carrying out large-scale investigations required to help determine the influence of cigarette design on smoking behaviors. To obtain more reasonable estimates of mainstream smoke exposure, we developed a method to quantitatively measure solanesol, a naturally occurring component in tobacco that is deposited during smoking in the cigarette filter butt. Quantification of solanesol extracted from the filters using liquid chromatography and tandem mass spectrometry is efficient, rapid, and extremely reliable. We found that the amount of solanesol deposited in a cigarette filter is related to the mainstream smoke deliveries of tar and nicotine under a variety of smoking conditions. In addition, the amount of solanesol trapped in the filter remains stable at least 4 weeks after smoking. Measuring solanesol in cigarette filters as an exposure marker provides a noninvasive means to obtain reasonable estimates of mainstream tar and nicotine smoke deliveries under a wide variety of smoking conditions.     

State legislators' perceptions of lobbyists and lobbying on tobacco control issues

OBJECTIVE: To determine state legislators' perceptions about health and tobacco lobbyists, their frequency of contact with these lobbyists, and the amount of campaign contributions from health professional organisations and the tobacco industry. DESIGN: Cross-sectional study. SUBJECTS: State legislators from North Carolina, Texas, and Vermont (USA), serving in 1994. MAIN OUTCOME MEASURES: Perceptions about lobbyists representing the tobacco industry, non-profit health organisations, and state medical societies with respect to their credibility, importance as sources of information, and persuasiveness; extent of lobbying activities; campaign contributions from health professional organisations and the tobacco industry. RESULTS: Almost all legislators reported that medical society and non-profit health organisation lobbyists are credible on tobacco issues and just over half believed that these lobbyists are important sources of information. More legislators said they could be persuaded by medical and health lobbyists than by tobacco lobbyists. Although health professional Political Action Committees (PACs) gave campaign contributions to more state legislators, and gave higher amounts on average, than tobacco PACs, legislators reported less contact with medical society lobbyists than tobacco lobbyists about tobacco issues. CONCLUSIONS: State legislators have positive attitudes toward lobbyists for non-profit health organisations and state medical societies regarding tobacco issues. These groups may be an underused resource for educating legislators about tobacco control measures.


     

CNTs in Optoelectronic Devices: New Structural and Photophysical Insights on Porphyrin‐DWCNTs Hybrid Materials

The preparation and physical characterization of diverse porphyrin‐derived double‐walled carbon nanotubes (DWCNTs) conjugates are described. A porphyrin molecule is covalently linked and physically adsorbed to COOH‐derived DWCNTs. The photophysical properties of all porphyrin‐CNTs derivatives are studied in solution and in polymeric matrices. Definitive experimental evidence for photoinduced electron and/or energy transfer processes involving the porphyrin chromophores and the CNT wall is not obtained, but solid‐state UV‐vis absorption profiles display electronic transitions fingerprinting J‐ and H‐ type aggregates, where porphyrin molecules intermolecularly interact “head‐to‐tail” and “face‐to‐face”, respectively. In parallel, molecular modeling based on force‐field simulations is performed to understand the structure of the porphyrin‐CNTs interface and the nature of the interactions between the porphyrins and the DWCNTs. Finally, multilayered ‐ type devices are fabricated with the aim of investigating the interaction of the porphyrin‐derived DWCNTs with poly(3‐hexylthiophene)‐pyrene matrices containing small amounts of 1‐[3‐(methoxycarbonyl)propyl]‐1‐phenyl‐[6.6]C₆₁.     

Improved rapid authentication of vanillin using δ13C and δ2H values

Vanilla still remains one of the most important and widely used flavours in the food industry and is also extensively employed by fragrance and pharmaceutical manufacturing companies. Natural vanilla flavour, extracted from the pods of the tropic orchid vanilla, is considerably more expensive than synthetic vanillin. The disparity of prices between natural vanillin and that derived from other sources has given rise to many cases of fraudulent adulteration, and for more than 30 years, strenuous efforts have been made to authenticate sources of vanillin. Stable isotope analysis is one of the most powerful analytical tools to distinguish between natural vanillin and that originating from other sources. Recently, a rapid and precise method for analysis of both δ¹³C and δ²H values of plant methoxyl groups has been published. Here, we report an application of the method for the control of authenticity of vanillin. Carbon and hydrogen stable isotope values of the vanillin molecule and vanillin methoxyl groups of vanillin samples of different origins including authentic and synthetic samples were measured. The results clearly show that use of this approach provides a rapid and reliable authenticity assessment of vanillin. The technique used for these studies is robust and rapid, involves minimum sample preparation and requires only a small amount of vanillin sample, usually 1 mg for stable carbon and 4 mg for stable hydrogen analysis.     

Conditioning of FRF measurements for use with frequency based substructuring

Frequency based substructuring approaches have been used for the generation of system models from component data. While numerical models show successful results, there have been many difficulties with actual measurements in many instances. Previous work has identified some of these typical problems using simulated data to incorporate specific measurement difficulties commonly observed along with approaches to overcome some of these difficulties.This paper presents the results using actual measured data for a laboratory structure subjected to both analytical and experimental studies. Various commonly used approaches are shown to illustrate some of the difficulties with measured data. A new approach to better condition the measured functions and purge commonly found data measurement contaminants is utilized to provide dramatically improved results.Several cases are explored to show the difficulties commonly observed as well as the improved conditioning of the measured data to obtain acceptable results.