Long-term viable bioaerosol sampling using a temperature- and humidity-controlled filtration apparatus,a laboratory investigation using culturable E. coli.

Sampling for culturable (e.g., viable) aerosolized microbes (bioaerosols) is a useful means to provide information for public health monitoring and studies. However, it is challenging to maintain microbe culturability when sampling at high flow rates (>12 L/min) and extended periods of time (≥4 h). We developed a first-generation, viable bioaerosol collection system (VBCS) utilizing temperature (T) and relative humidity (RH)–conditioned filtration at a flow rate of 25 L/min. A two-stage system of tube-in-shell Nafion? exchange units provides cooling to ≤10°C and RH conditioning to 80–95%. Aerosol particles are collected on a polyurethane nanofiber filter providing a physical collection efficiency of >95% for sizes 0.06–10 µm. The T and RH conditions at the collection filter are maintained, despite changes to ambient conditions. The initial testing of the VBCS was done under indoor, laboratory conditions with aerosolized, vegetative E. coli. A scenario of a 30-min challenge of bioaerosol followed by continued sampling of clean air for various times was used to judge culturability maintenance under extended-term sampling. An initial loss of culturability upon collection onto the filter was observed; 23 ± 13% relative to 4-mm all-glass impinger. However once collected, 98% of culturability was maintained for an additional 4.5 h of sampling. An exponential decay in culturability was observed from 8 h to 15 h of sampling. Also, 24-h cold storage of the filters collected was studied. The VBCS is based on the use of dry filter cassettes, needs minimal maintenance, and preserves culturability of vegetative bacteria for >4 h.

© 2017 RTI International and Aerosol Dynamics Inc.     

Synthesis of Adducts of PAH Diol Epoxide Metabolites in p53 Tumor Suppressor Gene Sites

The synthesis, structures, and mutagenic properties of benzo[a]pyrene-deoxyadenosine adducts in a sequence context related to the p53 gene are described.     

Obesity: Prevalence,Theories, Medical Consequences,Management, and Research Directions

Obesity and its associated disorders are a growing epidemic across the world. Many genetic, physiological, and behavioral factors play a role in the etiology of obesity. Diet and exercise are known to play a valuable role in the treatment and prevention of obesity and associated disorders such as hypertension, heart disease, and diabetes. Therefore, the purpose of this review is to examine the prevalence, etiology, consequences, and treatment of obesity.     

Thermal,mechanical, and diffusional properties of nylon 6/ABS polymer blends: Compatibilizer effect

The thermal, mechanical, and water absorption properties of blends of nylon 6 (PA6) and acrylonitrile‐butadiene‐styrene copolymer (ABS) with and without the compatibilizer maleic anhydride (MAH) were studied. Polymers were melt‐blended using a twin screw extruder, and injection molded into sheets. Tensile and impact properties, hardness, heat deflection resistance, and dimensional stability were enhanced by the incorporation of MAH. Synergistic effects were observed for tensile elongation and flexural properties. The melting temperature and the thermal stability were not significantly affected by the incorporation of MAH. The mechanical property enhancement by the introduction of compatibilizer was explained by the formation of a micro‐domain structure in the blends. The equilibrium water uptake increased with increasing concentration of PA6, and the diffusion coefficient was determined from the water transport kinetics at different temperatures. Activation energy was extracted from the temperature dependence of the diffusion coefficient. No compatibilizer effect was observed in the swelling behavior.     

Evaluation of oxidative stability of canola oils by headspace analysis

Lipid oxidation is a major factor affecting flavor quality and shelf life of vegetable oils. Oxidative stability is therefore an important criterion by which oils are judged for usefulness in various food applications. In this study a method based on headspace analysis was developed to evaluate relative oxidative stability of canola oils. The method does not require the use of chemicals, involves minimal sample preparation, and can be performed on a relatively small sample size in comparison with traditional wet chemical methods. Canola oils freshly extracted in the laboratory from different seed samples were subjected to accelerated oxidation and analyzed for PV by standard methods and headspace volatiles by solid phase microextraction/GC-MS. Forward stepwise regression analysis of the data revealed a relationship between PV and headspace concentration of the volatile lipid oxidation products hexanal and trans,trans-2,4-heptadienal. The PV calculated using this formula correlated (R ²=0.73) with those measured by conventional methods. Presented in part at the 96th Annual Meeting of the AOCS, 1–4 May 2005, Salt Lake City, UT.     

Influence of Mg Addition on the Catalytic Activity of Alumina Supported Ag for C3H6-SCR of NO

The influence of different magnesium (Mg) weight percentages (1, 2.5, 5, 7.5 and 10) over silver (3 wt%) impregnated alumina (SA) catalyst was investigated for the reduction of NO by C₃H₆. Mg doped SA catalysts were prepared by conventional impregnation method and characterized by XRD, BET-SA, ICP-MS, XPS, SEM, UV-DRS, H₂-TPR and O₂-TPD. The existence of MgO and MgAl₂O₄ phases on Mg doped SA catalysts were observed from XRD and XPS analyses. Existence of high percentage MgAl₂O₄ phase on 5% Mg doped SA catalyst (Mg (5) SA) enhances the dispersion and stabilization of silver phases (Ag₂O). Mg (5) SA catalyst shows a 51% of high selectivity (NO to N₂) in presence of SO₂ (80 ppm) at low temperatures (350 °C) and maintained high selectivity’s with a wide temperature window (350–500 °C). An optimal high surface availability of Ag⁰ and Ag⁺ species were observed from XPS analysis over Mg (5) SA catalyst. H₂-TPR analysis shows high temperature reduction peak over Mg (5) SA compared to SA catalyst. XPS analysis confirms the high percent availability of MgAl₂O₄ species over Mg (5) SA catalyst. DRIFTS study reveals the molecular evidences for the evolution of enolic species during NO reduction over the highly active Mg (5) SA catalyst at low temperatures. It also confirms further transformation of enolic species into –NCO species with NO + O₂ and finally into N₂ and CO₂.     

A high resolution XPS study of sidewall functionalized MWCNTs by fluorination

Carbon nanotubes must be modified to magnify their application. Understanding the chemistry of carbon nanotubes is a crucial step towards their ultimate practical use. In this study, multi-walled carbon nanotubes (MWCNTs) were fluorinated at several different conditions. The change in the atomic structures of fluorinated MWCNTs was investigated using X-ray photoelectron spectroscopy (XPS). All core level spectra of MWCNTs were deconvoluted to several Pseudo-Voigt functions (sum of Gaussian–Lorentzian functions). The amount of doped fluorine increased with increasing doping fluorine partial pressure, and the fluorine atoms were covalently attached to the side-wall of the MWCNTs. However, the increasing rate of F1s component ratio became dull at 70%, as compared with ratios below 70%. This suggests that fluorine contents during the fluorination of carbon materials can be managed by controlling the fluorine mixing ratio.     

Palladium‐Catalyzed Decarboxylative sp‐sp2 Cross‐Coupling Reactions of Aryl and Vinyl Halides and Triflates with α,β‐Ynoic Acids using Silver Oxide

Palladium‐catalyzed decarboxylative sp‐sp² cross‐coupling reactions of aryl and vinyl halides and triflates with α,β‐ynoic acids using silver oxide have been developed. A variety of α,β‐ynoic acids were readily decarboxylated in the presence of silver oxide and then, generated in situ, silver acetylides were coupled with electrophiles in the presence of a palladium(0) catalyst under neutral conditions, producing either symmetrical or unsymmetrical diarylacetylenes, arylalkylacetylenes and arylvinylacetylenes in good to excellent yields.     

Genotype and Growing Environment Effects on the Tocopherols and Fatty Acids of <Emphasis Type="Italic">Brassica napus</Emphasis> and <Emphasis Type="Italic">B. juncea</Emphasis>

The effects of genotype and growing environment on the tocopherols and fatty acids (FA) of experimental Brassica juncea and B. napus breeding lines were investigated. For both species, with the exception of a few genotypes, the concentration ratio of γ-tocopherols to α-tocopherol was practically constant. The genotype influenced the tocopherol concentration in B. napus, and to a lesser degree, B. juncea. The environment also had a similar effect, and a positive correlation existed between the daily maximum temperature and the α-tocopherol concentration in B. napus. Genotype effects on the FA composition were significant for the conventional but not for Clearfield or triazine tolerant traits of B. napus. The genotype had no effect on the FA of the B. juncea genotypes. In contrast, the growing environment had a significant influence on the FA composition of both species with apparent influence from temperature and rainfall. For both species, the concentration of γ-tocopherol as well as total tocopherols was inversely related to the 18:3 concentration, which could have resulted from opposite and independent effects of temperature on the two variables. No relationship existed between the concentrations of tocopherol and the remaining unsaturated FA 18:1 and 18:2. The positional distribution of unsaturated FA within the oil triacylglycerol was a function of their total concentration.     

Evaluation of corrosion rate from polarisation curves not exhibiting a Tafel region

Evaluation of corrosion rate by Tafel extrapolation is often impossible, simply because an experimental polarisation curve does not exhibit linear Tafel regions. This paper shows how such curves for the Fe/H₂O/H⁺/O₂ corrosion system can be accurately deconstructed to furnish both kinetic and thermodynamic parameters for the anodic and cathodic reactions. The curved anodic branch (due to film formation) is then amenable to correction for IR voltage drop and the resulting Tafel slope and other parameters are then substituted in the Tafel equation to accurately determine i_corr. An alternative method to obtain the anodic Tafel slope has been used to validate the above approach. Polarisation curves describing the inhibition of mild steel in industrial cooling water were scanned/digitised from the literature.