Probing functional groups at the gas-aerosol interface using heterogeneous titration reactions: a tool for predicting aerosol health effects?

The complex chemical and physical nature of combustion and secondary organic aerosols (SOAs) in general precludes the complete characterization of both bulk and interfacial components. The bulk composition reveals the history of the growth process and therefore the source region, whereas the interface controls--to a large extent--the interaction with gases, biological membranes, and solid supports. We summarize the development of a soft interrogation technique, using heterogeneous chemistry, for the interfacial functional groups of selected probe gases [N(CH(3))(3), NH(2)OH, CF(3)COOH, HCl, O(3), NO(2)] of different reactivity. The technique reveals the identity and density of surface functional groups. Examples include acidic and basic sites, olefinic and polycyclic aromatic hydrocarbon (PAH) sites, and partially and completely oxidized surface sites. We report on the surface composition and oxidation states of laboratory-generated aerosols and of aerosols sampled in several bus depots. In the latter case, the biomarker 8-hydroxy-2'-deoxyguanosine, signaling oxidative stress caused by aerosol exposure, was isolated. The increase in biomarker levels over a working day is correlated with the surface density N(i)(O3) of olefinic and/or PAH sites obtained from O(3) uptakes as well as with the initial uptake coefficient, γ(0), of five probe gases used in the field. This correlation with γ(0) suggests the idea of competing pathways occurring at the interface of the aerosol particles between the generation of reactive oxygen species (ROS) responsible for oxidative stress and cellular antioxidants.

Comparative genome analysis of Pseudomonas knackmussii B13, the first bacterium known to degrade chloroaromatic compounds.

Pseudomonas knackmussii B13 was the first strain to be isolated in 1974 that could degrade chlorinated aromatic hydrocarbons. This discovery was the prologue for subsequent characterization of numerous bacterial metabolic pathways, for genetic and biochemical studies, and which spurred ideas for pollutant bioremediation. In this study, we determined the complete genome sequence of B13 using next generation sequencing technologies and optical mapping. Genome annotation indicated that B13 has a variety of metabolic pathways for degrading monoaromatic hydrocarbons including chlorobenzoate, aminophenol, anthranilate and hydroxyquinol, but not polyaromatic compounds. Comparative genome analysis revealed that B13 is closest to Pseudomonas denitrificans and Pseudomonas aeruginosa. The B13 genome contains at least eight genomic islands [prophages and integrative conjugative elements (ICEs)], which were absent in closely related pseudomonads. We confirm that two ICEs are identical copies of the 103 kb self-transmissible element ICEclc that carries the genes for chlorocatechol metabolism. Comparison of ICEclc showed that it is composed of a variable and a 'core' region, which is very conserved among proteobacterial genomes, suggesting a widely distributed family of so far uncharacterized ICE. Resequencing of two spontaneous B13 mutants revealed a number of single nucleotide substitutions, as well as excision of a large 220 kb region and a prophage that drastically change the host metabolic capacity and survivability.

Oxidative potential of particles in different occupational environments: a pilot study

The oxidative potential (OP) of particulate matter has been proposed as a toxicologically relevant metric. This concept is already frequently used for hazard characterization of ambient particles but it is still seldom applied in the occupational field. The objective of this study was to assess the OP in two different types of workplaces and to investigate the relationship between the OP and the physicochemical characteristics of the collected particles. At a toll station, at the entrance of a tunnel ('Tunnel' site), and at three different mechanical yards ('Depot' sites), we assessed particle mass (PM4 and PM2.5 and size distribution), number and surface area, organic and elemental carbon, polycyclic aromatic hydrocarbon (PAH), and four quinones as well as iron and copper concentration. The OP was determined directly on filters without extraction by using the dithiothreitol assay (DTT assay-OP(DTT)). The averaged mass concentration of respirable particles (PM4) at the Tunnel site was about twice the one at the Depot sites (173±103 and 90±36 µg m(-3), respectively), whereas the OP(DTT) was practically identical for all the sites (10.6±7.2 pmol DTT min(-1) μg(-1) at the Tunnel site; 10.4±4.6 pmol DTT min(-1) μg(-1) at the Depot sites). The OP(DTT) of PM4 was mostly present on the smallest PM2.5 fraction (OP(DTT) PM2.5: 10.2±8.1 pmol DTT min(-1) μg(-1); OP(DTT) PM4: 10.5±5.8 pmol DTT min(-1) μg(-1) for all sites), suggesting the presence of redox inactive components in the PM2.5-4 fraction. Although the reactivity was similar at the Tunnel and Depot sites irrespective of the metric chosen (OP(DTT) µg(-1) or OP(DTT) m(-3)), the chemicals associated with OP(DTT) were different between the two types of workplaces. The organic carbon, quinones, and/or metal content (Fe, Cu) were strongly associated with the DTT reactivity at the Tunnel site whereas only Fe and PAH were associated (positively and negatively, respectively) with this reactivity at the Depot sites. These results demonstrate the feasibility of measuring of the OP(DTT) in occupational environments and suggest that the particulate OP(DTT) is integrative of different physicochemical properties. This parameter could be a potentially useful exposure proxy for investigating particle exposure-related oxidative stress and its consequences. Further research is needed mostly to demonstrate the association of OP(DTT) with relevant oxidative endpoints in humans exposed to particles.

Decomposição catalítica de óleo de soja em presença de diferentes zeólitas

The catalytic decomposition of soybean oil was studied in a fix bed reactor at 673 and 773 K and using amorphous silica-alumina and the zeolites USY, H-Mordenite and H-ZSM-5 as catalysts. Both the selectivity and the catalytic activity were determined by studying the product composition resulting from the chemical reactions. Physicochemical characteristics of the catalysts were obtained by X-ray fluorescence, Fourier Transform infrared spectroscopy, 29Si and 27Al Nuclear Magnetic Ressonance and textural analysis. The zeolites USY and H-ZSM-5, showing higher Brönsted acidity, yielded products with higher concentration in aromatic hydrocarbons, whereas with both H-Mordenite and amorphous silica-alumina the main products were paraffins.

Caracterização de amostras petroquímicas e derivados utilizando cromatografia gasosa bidimensional abrangente (GCxGC)

The goal of this article is to discuss the application of comprehensive two-dimensional gas chromatography (GCxGC) to petrochemical samples. The use of GCxGC for petroleum and petroleum derivatives characterization, through group type analysis, or BTEX (benzene, toluene, ethylbenzene, xylenes), total aromatic hydrocarbons, polyaromatic hydrocarbons, sulfur-containing, oxygen-containing, and nitrogen-containing compounds is presented. The capability of GCxGC to provide additional specific chemical information regarding petroleum processing steps, such as dehydrogenation of linear alkanes, the Fischer-Tropsch process, hydrogenation and oligomerization is also described. In addition, GCxGC analyses of petrochemical biomarkers and environmental pollutants derived from petrochemicals are reported.

Avaliação do destino e bioacumulação de benzo(a)pireno através de simulação computacional

The objective of this work was to evaluate the environmental distribution of benzo(a)pirene, a polycyclic aromatic hydrocarbon, by the EQC model. The modeling of the contaminant distribution was accomplished by means of the fugacity model applied to a hypothetical scenario constituted by air, water, soil and sediment. The modeling and simulations revealed that the soil is the preferential compartment. We also discuss the implications of the results about fate and ecological risks associated with benzo(a)pirene. We concluded that the emissions of HPAs can not be ignored and bioaccumulation among others risks can be induced.

Técnicas de extrações e procedimentos de clean-up para a determinação de hidrocarbonetos policílicos aromáticos (HPA) em sedimentos da costa do Ceará

Extraction and clean-up are essential points in polycyclic aromatic hydrocarbon (PAHs) analysis in a solid matrix. This work compares extraction techniques and clean-up procedures for PAH analysis. PAH levels, their toxicological significance and source were also evaluated in the waters of the Cocó and Ceará rivers. The efficiency of PAH recovery was higher for the soxhlet and ultrasonic techniques. PAH recovery varied from 69.3 to 99.3%. Total PAH concentration (ΣHPA) varied from 720.73 to 2234.76 µg kg-1 (Cocó river) and 96.4 to 1859.21 µg kg-1 (Ceará river). The main PAH sources are pyrolytic processes and the levels were classified as medium so that adverse effects are possible.

Degradação de benzeno, tolueno e xilenos em águas contaminadas por gasolina, utilizando-se processos foto-Fenton

In this work the potentiality of photo-Fenton processes were investigated toward the degradation of aromatic hydrocarbons (BTXs) from water contaminated with gasoline. The main results demonstrated that BTXs can be quickly degraded by photo-Fenton process assisted by solar or artificial UV-A radiation, degradation that leads to generation of characteristic phenolic transient species (ie. phenol, hydroquinone and catechol). In the treatment of contaminated water by photo-Fenton processes assisted by solar light, complete BTXs removal was observed in reaction times of about 5 min. Mineralization of about 90% was also observed by applying a multiple H2O2 addition system.

Chemical constituents of Salacia elliptica (Celastraceae)

The chemical investigation of Salacia elliptica allowed to the isolation of 20 constituents: two polyols, one xanthone, a mixture of long chain hydrocarbons, one carboxylic acid, one polymer, two steroidal compounds, one aromatic ester and eleven pentacyclic triterpenes. These triterpenes include 3β-stearyloxy-oleanane, 3β-stearyloxy-ursane, one seco-friedelane, and eight compounds of the friedelane serie. The chemical structure and the relative configuration of a new triterpene 1,3-dioxo-16α-hydroxyfriedelane (15) were established through ¹H and 13C NMR including 2D experiments (HMBC, HMQC, COSY and NOESY) and herein reported for the first time.

Impacto ambiental de kartódromos situados na cidade do Rio de Janeiro: monitoramento de BTEX no ar e do nível de ruído

In this work, noise and aromatic hydrocarbons levels of indoor and outdoor karting circuits located in Rio de Janeiro were assessed. The sampling was perfomed using active charcoal cartridges, followed by solvent desorption and analysis by gas chromatography with mass spectrometry detection. This study demonstrated that the karting circuits, venues for entertainment, were a major source of air pollution with the detection of considerable amounts of these compounds (2.0 to 19.7 µg m-3 of benzene; 4.1 to 41.1 µg m-3 of toluene; 2.8 to 36.2 µg m-3 of ethylbenzene; 0.7 to 36.2 µg m-3 of xylenes) and high noise levels.

Avaliação da eficiência de degradação de hidrocarbonetos aromáticos por bactérias provinientes de estação de tratamento de efluente de refinaria de petróleo

Three bacterial strains were isolated from the activated sludge system of petroleum refinery wastewater, identified by partial sequencing of 16S rDNA, and classified as Acinetobacter genomospecies 3, Bacillus pumilus, and Bacillus flexus. The degradation efficiency of aromatic hydrocarbons was evaluated by gas chromatography with a flame ionization detector. In a mineral medium containing anthracene and phenanthrene and the consortium of microorganisms, the removal efficiency was 96% and 99%, respectively, after 30 days. The good rate of hydrocarbon degradation proves the operational efficiency of the microbial consortium in treating effluents containing these compounds.

ORGANIC MATTER AND HUMIC FRACTIONS OF A HAPLIC ACRISOL AS AFFECTED BY COMPOSTED PIG SLURRY

The goal of this study was to investigate the effect of composted pig slurry (PS) on the organic matter concentration and distribution of humic acid (HA), fulvic acid (FA) and humin (HU) fractions. The fractions were quantified following the addition of composted PS to the soil, which was produced with no acidification (T2) or with acidification with H3PO4 (T3); and in soil without compost addition (T1). The HA chemical composition was analyzed by FTIR spectroscopy. The addition of the two composts did not change the soil carbon concentration but affected the distribution of the humic fractions. For the three treatments, the carbon concentration of humic substances increased until 52 days following compost addition, with more pronounced increases with the addition of non-acidified PS compost (14.5 g kg-1) and acidified PS compost (15.1 g kg-1). This increase was reflected in both the FA and HA concentrations. The addition of compost with PS acidification resulted in the formation of larger humic micelles (HA) with higher aromatic content and fewer functional groups than the non-acidified PS compost. These findings, together with a lower proportion of carbohydrate-type structures, indicated the presence of more stable humic micelles in the soil treated with acidified PS compost.

Deoxygenation of fatty acids for production of fuels and chemicals

The decreasing fossil fuel resources combined with an increasing world energy demand has raised an interest in renewable energy sources. The alternatives can be solar, wind and geothermal energies, but only biomass can be a substitute for the carbon–based feedstock, which is suitable for the production of transportation fuels and chemicals. However, a high oxygen content of the biomass creates challenges for the future chemical industry, forcing the development of new processes which allow a complete or selective oxygen removal without any significant carbon loss. Therefore, understanding and optimization of biomass deoxygenation processes are crucial for the future bio–based chemical industry. In this work, deoxygenation of fatty acids and their derivatives was studied over Pd/C and TiO2 supported noble metal catalysts (Pt, Pt–Re, Re and Ru) to obtain future fuel components. The 5 % Pd/C catalyst was investigated in semibatch and fixed bed reactors at 300 °C and 1.7–2 MPa of inert and hydrogen–containing atmospheres. Based on extensive kinetic studies, plausible reaction mechanisms and pathways were proposed. The influence of the unsaturation in the deoxygenation of model compounds and industrial feedstock – tall oil fatty acids – over a Pd/C catalyst was demonstrated. The optimization of the reaction conditions suppressed the formation of by–products, hence high yields and selectivities towards linear hydrocarbons and catalyst stability were achieved. Experiments in a fixed bed reactor filled with a 2 % Pd/C catalyst were performed with stearic acid as a model compound at different hydrogen–containing gas atmospheres to understand the catalyst stability under various conditions. Moreover, prolonged experiments were carried out with concentrated model compounds to reveal the catalyst deactivation. New materials were proposed for the selective deoxygenation process at lower temperatures (~200 °C) with a tunable selectivity to hydrodeoxygenation by using 4 % Pt/TiO2 or decarboxylation/decarbonylation over 4 % Ru/TiO2 catalysts. A new method for selective hydrogenation of fatty acids to fatty alcohols was demonstrated with a 4 % Re/TiO2 catalyst. A reaction pathway and mechanism for TiO2 supported metal catalysts was proposed and an optimization of the process conditions led to an increase in the formation of the desired products.

Polymorphism of the aryl-hydrocarbon receptor gene in intron 10 of human cancers

Polychlorinated dibenzo-p-dioxins (PCDDs) and related halogenated aromatic hydrocarbons (e.g., PCDFs), often called "dioxins", are ubiquitously present environmental contaminants. Some of them, notably 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are among the most toxic synthetic compounds known. The biological effects of dioxins are mediated via the aryl hydrocarbon receptor (AhR). Mutations in the AhR transactivation domain are linked to sensitivity to the acute lethality of TCDD. We present here a study of AhR gene polymorphism in normal and cancer human tissues affecting pre-mRNA splicing in the AhR gene-coding transactivation domain region (exon 10, intron 10, exon 11 region), previously shown to be associated with AhR dysfunction. We tested 126 pairs of normal and cancer tissue samples from liver, lung, stomach, kidney, mucous, breast, and pancreas of 49 males and 77 females (45-70 years of age). We used in vitro splicing assay, RT-PCR and sequencing methods. Our results showed that in an in vitro system it is possible to reconstitute cellular pre-mRNA splicing events. Tested cancer tissues did not contain mutations in the AhR transactivation domain region when the DNA sequences were compared with those from normal tissues. There were also no differences in AhR mRNA splice variants between normal and malignant breast tissues and no polymorphisms in the studied regions or cDNA.

Evaluation of quality factors of bovine and chicken meat marinated with reduced sodium content

In many industrialized countries, including Brazil, sodium intake exceeds the nutritional recommendations. Excessive consumption is associated with hypertension and premature death by cardiovascular diseases. The industry's challenge is to produce products with reduced sodium that are similar to regular products in texture and flavor and consistent with consumers' dietary habits. The present study aimed at substituting 25 and 50% NaCl for KCl in marinated beef and chicken meat with the addition of aromatic herbs and spices. The following microbiological analyses were carried out: macronutrient, chemical composition, and sensorial analysis. The meats showed a reduction in NaCl contents without any changes in their physical and chemical characteristics, and the products´ quality and microbiological safety were maintained. Beef and chicken tenderness was maintained for both treatments. Furthermore, the use of 50% KCl did not cause any changes in the products' sensory quality, and the overall acceptance of both types of meat was maintained. Results showed that a reduction by 50% in the NaCl contents of marinated meat products with a combination of herbs and spices is possible. Future applications in other meat products and sausages are highly promising.