Abstract  Pseudomonas monteilii CCM 3423 bacterial strain, deposited at the Czech Collection of Microorganisms, was originally isolated by Haľama and Augustín (1980) as a bacterium degrading aromatic hydrocarbons and derivates. A detailed study supported by a molecular genetics method of sequence analyses of rrs and rpoD genes was used to reclassify the strain, originally stored as 'Pseudomonas putida'. The physiological characteristics of the strain are complemented with research in the capacity to utilize selected organic pollutants (anthracene, benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, fluorene, naphthalene, phenanthrene). The obtained results point at very good biodegradation properties of the strain. Already after 7 days of the bacterial strain's action, there was a decrease in all the organic contaminants to 79.8 ± 2.6 %. In 14 days, the amount of organic contaminants dropped to 59.3 ± 2.8 %. After 21 days of biodegradation experiments, the overall quantity of the observed organic substances fell below the half limit to 45.7 ± 2.5 % of residuals. Finally, after 28 days, the residue was 35.4 ± 2.2 %, and after 35 days of the action of P. monteilii, the tested samples contained mere 27.8 ± 2.8 % of organic pollutants. The results imply that Pseudomonas monteilii CCM 3423 is a prospective strain in terms of further biotechnological application in contaminated environment.

Abstract  The aquatic biota of the Arabian Gulf deals with exposure to chronic oil pollution, several constituents of which cause induction of Cytochrome P450 1A that serves as a biomarker of AhR ligand exposure. In this study, fluorescent aromatic compounds (FACs) in bile and 7-ethoxyresorufin-o-deethylase (EROD) catalytic activity were determined as a measure of exposure biomarkers in two fish species, yellow fin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) captured from Kuwait Bay and outside the Bay area. FACs in fish bile determined by using fixed-wavelength fluorescence (FF) showed high fluorescence ratios between FF290/335 and FF380/430 indicating predominant exposure to low molecular weight, naphthalene-rich petroleum products (375±91.0pgml(-1)). Exposures to benzo(a)pyrene-type high-molecular weight polycyclic aromatic hydrocarbons (PAHs) originating from burnt fuel were also present in appreciable concentration in the bile. The ratio of petrogenic to pyrogenic hydrocarbon was twofold higher in winter compared to summer months in both species. Seasonal effect on EROD was significant in tonguesole in Auha site (P<0.05); whereas seabream resisted seasonal change. Tonguesole is considered to be a suitable bioindicator of oil pollution in Kuwait Bay area.

Abstract  Polycyclic aromatic hydrocarbons are organic compounds with highly toxic, carcinogenic, and mutagenic properties, which adversely affect the basic biological parameters of the soil, including the count of microorganisms, and the enzymatic activity. In addition to disturbances to the biological activity of the soil, PAHs may also exhibit toxic effects on plants. In view of the above, the study involved testing aimed at the determination of the effects of polycyclic aromatic hydrocarbons in a form of naphthalene, phenanthrene, anthracene and pyrene on the count, colony development (CD) index, ecophysiological (EP) diversity index of organotrophic bacteria, and the activity of soil dehydrogenases and soil urease. Moreover, an attempt was made to determine the soil's resistance based on the activity of the above-listed enzymes, and the effect of polycyclic aromatic hydrocarbons on seed germination and root growth was assessed by Lepidium sativum, Sorghum saccharatum, and Sinapis alba. In addition, the species of bacteria found in a soil subjected to strong pressure of polycyclic aromatic hydrocarbons were isolated. The experiment was performed in a laboratory on samples of loamy sand. Polycyclic aromatic hydrocarbons were introduced into the soil in an amount of 0, 1000, 2000, and 4000 mg kg(-1) of soil dry matter. Germination and growth of cress (L. sativum), white mustard (S. alba), and sweet sorghum (S. saccharatum) were determined using Phytotoxkit tests. It was found that the tested PAHs increased the average colony counts of organotrophic soil bacteria; pyrene did so to the greatest extent (2.2-fold relative to non-contaminated soil), phenanthrene to the smallest extent (1.4-fold relative to non-contaminated soil). None of the PAHs changed the value of the bacterial colony development (CD) index, while anthracene and pyrene increased the value of the eco-physiological (EP) diversity indicator. PAHs lowered the activity of the tested enzymes. The activity of dehydrogenases was dependent on a greater extent by the type of hydrocarbon (54.56 %) rather than by the dose (10.64 %), while for the activity of urease, it was the opposite. The greater extent was dependent on dose (95.42 %) rather than by type (0.21 %). Dehydrogenases are characterised by greater resistance to the action of PAHs than urease. Based on seed germination and root growth, it has shown that S. alba is best suited, being the most vulnerable plant, while S. saccharatum is the least suited. Subjecting a soil to strong pressure of PAHs leads to disturbances to the biological parameters of the soil, seed germination, and root growth L. sativum, S. saccharatum, and S. alba.

Abstract  If quantum interference patterns in the hearts of polycyclic aromatic hydrocarbons could be isolated and manipulated, then a significant step toward realizing the potential of single-molecule electronics would be achieved. Here we demonstrate experimentally and theoretically that a simple, parameter-free, analytic theory of interference patterns evaluated at the mid-point of the HOMO-LUMO gap (referred to as M-functions) correctly predicts conductance ratios of molecules with pyrene, naphthalene, anthracene, anthanthrene, or azulene hearts. M-functions provide new design strategies for identifying molecules with phase-coherent logic functions and enhancing the sensitivity of molecular-scale interferometers.

Abstract  The mechanism of the formation of aggregates between a protein, bovine serum albumin (BSA), and alkyltrimethylammonium bromides of varied hydrocarbon chain lengths, namely, cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB), and dodecyltrimethylammonium bromide (DTAB) in an aqueous solution and the physicochemical characteristics of the aggregates were systematically investigated by surface tensiometry, fluorimetry, UV-vis spectrometry, dynamic light scattering, zeta potential, and differential scanning calorimetry (DSC). The surface tension and fluorimetry data indicate a steady decrease in the critical micelle concentrations of the surfactants with an increase in the amount of BSA in the mixture. The evolution of an additional nonpolar segment in the backbone of BSA was indicated by the fluorescence of pyrene and the intrinsic fluorescence of BSA as well. The decrease in the aggregation number, increase in the area per molecule of the surfactant at the interface with a concomitant increase in the hydrodynamic radius of the aggregate were attributed to the formation of BSA-surfactant mixed aggregate and the induction of the unfolding of BSA by the surfactants. The DSC study and nature of the denaturation curves of BSA indicate that the stability of the BSA-surfactant complex follows the order: CTAB. >. TTAB. >. DTAB. The neutralization of the negatively charged surface of BSA by the positively charged surfactants is evident from the zeta potential measurements. Both the head group and nonpolar moiety of the surfactants affected the surface charge of the aggregates and the studied surfactants denature and unfold BSA; the extent of denaturation is predominately decided by the hydrocarbon chain length of the former. The in situ unfolding of the protein and the subsequent formation of the aggregates are proposed. The characteristic parameters of the aggregates were determined. © 2015 Elsevier B.V.

Abstract  The influence of temperature on the bioaccumulation, toxicokinetics, biotransformation and depuration of pyrene was studied in the arctic marine amphipod Gammarus setosus. A two-compartment model was used to fit experimental values of total body burden, total metabolites and parent pyrene concentrations and to calculate toxicokinetic variables derived for two experimental treatments (2 and 8 degrees C). No statistically significant differences were observed with temperature for these toxicokinetic variables or bioconcentration factors. Contrarily, the Q(10) values suggested that the toxicokinetic variables k(e) and k(m) were temperature-dependent. This may be explained by the high standard deviation of the Q(10) values. Q(10) is the variation in the rate of a metabolic reaction with a 10 degrees C increase in temperature. Depuration rate constants were calculated from linear best fit equations applied to measured pyrene concentrations over time during the depuration phase of the experiment. During depuration, the parent pyrene was eliminated in two stages with faster elimination observed at 8 degrees C compared to 2 degrees C. This finding was also indicated by the Q(10). No changes in total body burdens of metabolite concentrations were observed during the monitoring of depuration over a period of 96 h. The biotransformation pathway of pyrene in G. setosus was also investigated in this study with two main phase II biotransformation products discovered by liquid chromatography. These products are conditionally identified as the sulphate and glucose conjugates of 1-hydroxy-pyrene. Overall, the study contributes new knowledge to the understanding of the fate of PAHs in arctic biota. In particular, the study provides valuable insight into the bioaccumulation and biotransformation of an important PAH and its metabolites in a species that serves as both a predator and prey in the arctic ecosystem. (C) 2015 Elsevier Ltd. All rights reserved.

Abstract  Classical chemical dynamics simulations, were performed to study the intramolecular and unimolecular dissociation dynamics of the benzene dimer, Bz(2) -> Bz. The dissociation of microcanonical ensembles of Bz(2) vibrational states, at energies E corresponding to temperatures T of 700-1500 K, were simulated. For the large Bz(2) energies and large number of Bz(2) vibrational degrees of freedom, s, the classical microcanonical (RRKM) and canonical (TST) rate Constant expressions become identical. The dissociation rate constant for each T is determined from the initial rate dN(t)/dt of Bz(2) dissociation, and the k(T) are well-represented by the Arrhenius eq-k(T) = A -exp(-E-a/RT). The E-a of 2.02 kcal/mol agrees well with the Bz(2) disseciation energy 2.32 kcal/mol, and the A,factor of 2.43 X 10(12) s(-1) is of the expected order-Of-magnitude. The form of N(t) is nonexponential, resulting from weak coupling, between the Bz(2) intramolecular and intermolecular nodes. With this weak coupling, large Bz(2) vibrational excitation, and low Bz(2) dissociation energy, most of the trajectories dissociate directly. Simulations, with only the Bz(2) intramolecular modes excited at 1000 K, were also performed to study intramolecular Vibrational energy redistribution,(IVR) between. the intramolecular and intermolecular modes. Because of restricted IVR, the initial dissociation is quite slow, but N(t) ultimately becomes exponential, suggesting an IVR time of 20.7 ps.

Abstract  A novel ultrasonic nebulization extraction/low-pressure photoionization (UNE-LPPI) system has been designed and employed for the rapid mass spectrometric analysis of chemicals in matrices. An ultrasonic nebulizer was used to extract the chemicals in solid sample and nebulize the solvent in the nebulization cell. Aerosols formed by ultrasonic were evaporated by passing through a transferring tube, and desolvated chemicals were ionized by the emitted light (10.6 eV) from a Krypton discharge lamp at low pressure (∼68 Pa). First, a series of semi/non-volatile compounds with different polarities, such as polycyclic aromatic hydrocarbons (PAHs), amino acids, dipeptides, drugs, nucleic acids, alkaloids, and steroids were used to test the system. Then, the quantification capability of UNE-LPPI was checked with: 1) pure chemicals, such as 9,10-phenanthrenequinone and 1,4-naphthoquinone dissolved in solvent; 2) soil powder spiked with different amounts of phenanthrene and pyrene. For pure chemicals, the correlation coefficient (R(2)) for the standard curve of 9,10-phenanthrenequinone in the range of 3 ng-20 μg mL(-1) was 0.9922, and the measured limits of detection (LOD) was 1 ng ml(-1). In the case of soil powder, linear relationships for phenanthrene and pyrene from 10 to 400 ng mg(-1) were obtained with correlation coefficients of 0.9889 and 0.9893, respectively. At last, the feasibility of UNE-LPPI for the detection of chemicals in real matrices such as tablets and biological tissues (tea, Citrus aurantium peel and sage (Salvia officinalis) leaf) were successfully demonstrated.

Abstract  Aqueous micellar solutions of bile salts, sodium cholate (NaC) (1-30 mmol kg(-1)) and sodium deoxycholate.(NaDC) (1-17 mmol kg(-1)) in the absence and presence of amino acids viz. glycine, leucine, methionine, and histidine (0.1 mol kg(-1)) have been examined by surface tension and UV-visible measurements at different temperatures (293.15-318.15 K). From the surface tension study, critical micelle concentration (CMC) values of bile salts have been calculated and reviewed in terms of effect of amino acids on the hydrophobic character of bile salt-amino acid complex. Further, the adsorption behavior of NaC and NaDC in aqueous solution of amino acids has been analyzed with the help of interfacial parameters like maximum surface excess concentration (Gamma(max)), minimum area per surfactant molecule (A(min)), surface pressure at CMC (Pi(CMC)), efficiency in reducing surface tension (pC(20)), and adsorption at the air/water interface relation to micellization (CMC/C-20). The thermodynamic parameters, standard free energy of micellization (Delta G(m)degrees), standard Gibb's free energy of adsorption (Delta G(ad)degrees), and standard free energy of transfer (Delta G(tr)degrees) have also been calculated. UV-visible studies, by using pyrene as a probe, have also been carried out in order to substantiate the CMC values derived from surface tension studies. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  BACKGROUND: The Deep Water Horizon oil spill of 2010, prompted concern about health risks among seafood consumers exposed to polycyclic aromatic hydrocarbons (PAHs) via consumption of contaminated seafood.

OBJECTIVE: To conduct population-specific probabilistic health risk assessments based on consumption of locally harvested white shrimp (Litopenaeus setiferus) among Vietnamese-Americans in Southeast Louisiana.

METHODS: We conducted a survey of Vietnamese-Americans in Southeast Louisiana, to measure shrimp consumption, preparation methods, and bodyweight among shrimp consumers in the disaster-impacted region. We also collected and chemically analyzed locally harvested white shrimp for 81 individual PAHs. We combined the PAH levels (with accepted reference doses) found in the shrimp with the survey data to conduct Monte Carlo simulations for probabilistic non-cancer health risk assessments. We also conducted probabilistic cancer risk assessments using relative potency factors (RPFs) to estimate cancer risks from the intake of PAHs from white shrimp.

RESULTS: Monte Carlo simulations were used to generate hazard quotient distributions for non-cancer health risks, reported as mean ± standard deviation, for naphthalene (1.8 x 10(-4) ± 3.3 x 10(-4)), fluorene (2.4 x 10(-5) ± 3.3 x 10(-5)), anthracene (3.9 x 10(-6) ± 5.4 x 10(-6)), pyrene (3.2 x 10(-5) ± 4.3 x 10(-5)), and fluoranthene (1.8 x 10(-4) ± 3.3 x 10(-4)). A cancer risk distribution, based on RPF-adjusted PAH intake, was also generated (2.4 x 10(-7) ± 3.9 x 10(-7)).

CONCLUSIONS: The risk assessment results show no acute health risks or excess cancer risk associated with consumption of shrimp containing levels of PAHs detected in our study, even among frequent shrimp consumers. 

Abstract  A biomonitoring study was performed employing standardized grass cultures. Plants of Lolium multiflorum were exposed at 4 industrial sites over three-month periods in two seasons (dry and rainy) and the biomass produced was used for subsequent measurements of fluoride, polycyclic aromatic hydrocarbons (phenanthrene, anthracene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene), total chlorophyll, malondialdehyde, water, and sulfur content. The total content of polycyclic aromatic hydrocarbons (PAHs) revealed seasonal variations, with the highest values corresponding to the dry season, although this species showed a high retention capacity of PAHs during rainy season. In addition, sampling sites with high vehicular traffic and metal-mechanical industries were associated with the highest content of PAHs. Furthermore, physiological degradation associated with anthropogenic activities in the sampling sites was observed. Fluoride content in the biomonitor was associated with the production and use of cement, which was higher in the dry season.

Abstract  The concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) in total suspended particulates (TSP) and soil were measured at a traffic site in Hanoi, a typical motorcycle city of Vietnam. TSP was collected using high-volume air sampler on Pallflex 2500QAT-UP membrane filters. PAHs and NPAHs were analyzed by high-performance liquid chromatography (HPLC) using fluorescence and chemiluminescence detectors, respectively. The average concentrations of total 10 PAHs and 10 NPAHs in soil varied from 3.4-43.7ng g(-1) and from 112-780 pg g(-1) dry weight, respectively, which were much lower than those in TSP. The results showed that large part of the higher molecular weight PAHs in soil, especially benzo[ghi]perylene and benzo[b]fluoranthene came from the atmosphere. However, NPAHs profile showed a different pattern. 3-nitroperylene and 6-nitrochrysene were the most abundant NPAHs in soil, followed by 1-nitropyrene and 6-nitrobenzo[a]pyrene. The fate of NPAHs in soil varied depending on soil properties and chemical structure of NPAHs. The finding that the [NPAH]/[PAH] concentration ratios in soil were different from those in TSP could be due to bio-degradation and/or secondary formation of NPAHs in soil, depending on NPAHs properties.

Abstract  The past several decades have witnessed a significant expansion of mining activities in the Athabasca oil sands region, raising concerns about their impact on the surrounding boreal forest ecosystem. To better understand the extent to which distal sites are impacted by oil sands-derived airborne contaminants, we examine sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and dated sediment cores from Saskatchewan lakes situated similar to 100-220 km east-northeast of the main area of bitumen mining activities. The concentrations and fluxes of both parent and alkylated PAHs are low and show considerable variability over the past 70-100 years. Small yet discernible increases in PAH concentrations and fluxes occurred over the past 30 years, a trend which coincides with the rapid growth in bitumen production. However, several lines of evidence point to wildfires as the principal source of PAHs to these lakes: (1) the significant co-variations in most cores between retene (1-methyl-7-isopropyl phenanthrene) and other groups of parent and alkylated PAHs, (2) the similarity in compound specific delta C-13 signatures of the parent PAHs phenanthrene and pyrene in recently deposited surficial sediments and those corresponding to time intervals considerably pre-dating the large scale development of the oil sands and (3) the discernible up-core increases in the proportion of refractory carbon (i.e., char) in Rock-Eval 6 data. The collective evidence points to softwood combustion from boreal forest fires as the principal source of retene in sediments and the general increase in forest fire activity in this region over the past several decades as the source of refractory carbon. Mining activities associated with the Athabasca oil sands are thus not considered a major source of PAHs to these lakes. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.

Abstract  Given the upcoming EURO 6 regulations, which include limits on particle number density (and hence size) for soot emissions from land vehicles, soot models must be capable of accurately predicting soot particle sizes. Previous modeling work has demonstrated the importance of the relative strengths of nucleation and condensation in predicting soot primary particle size; however, fundamental models still rely on tunable constants for modeling both processes, which limits predictive capability. Recent investigations into nucleation and condensation processes suggest that both processes are not thermodynamically favored to occur from 5-ringed PAHs, yet 5-ringed PAHs have been experimentally observed in abundance within nascent soot particles. This contradiction leads to the understanding that nucleation and condensation from 5-ringed PAHs is plausible, although they are likely highly reversible processes.

A fundamental reversible model for nucleation and condensation is developed through the use of statistical mechanics and the results from several recent works. The model is highly sensitive to both the binding energy and the vibration frequencies created during the nucleation and condensation processes, although reasonable values are obtained through an extensive literature review. A model for tracking the PAHs on the surface of soot particles is developed, which allows for the calculation of the reverse rate of nucleation and condensation. The inclusion of reversibility in the nucleation and condensation subroutines enables the model to accurately reproduce all relevant soot morphological parameters determined experimentally for the atmospheric pressure, laminar, ethylene-air Santoro flame. This is due to more accurate partitioning of PAH mass through the nucleation and condensation processes. The developed reversible model represents an advancement in fundamental soot formation modeling by replacing tunable constants with fundamental physics. (C) 2014 Published by Elsevier Inc. on behalf of The Combustion Institute.

Abstract  beta-cyclodextrin (beta-CD) functionalized CdTe quantum dots (QDs) were prepared with beta-CD and mercaptopropionic acid (MPA) as the stabilizers (denoted as beta-CD-MPA-CdTe). The QDs capped with the dual stabilizers, beta-CD and MPA, not only showed improved electrochemiluminescence (ECL) efficiency and higher ECL intensity due to the effective removal of the nonradiative surface state and deep surface trap of the QDs, but also exhibited selective response toward benzo[a]pyrene (BaP) as a consequence of specific host-guest interaction between the beta-CD and BaP, resulting in decreased ECL of the QDs. On the basis of the quenching effect of BaP on the ECL of beta-CD-MPA-CdTe QDs, a sensitive and selective method for the determination of BaP was developed. Under optimal conditions, a linear range from 87 pM to 10 nM with a detection limit of 29 pM (S/N = 3) was obtained for the detection of BaP. (C) 2015 Elsevier Ltd. All rights reserved.

Abstract  This paper investigates the effects of emissions including carcinogenic polycyclic aromatic hydrocarbons (cPAH) of a conventional diesel engine without a particle filter. Experiments were carried on during extended idle and during a loaded operation immediately following the extended idle. Extended low-load operation of diesel engines due to idling and creep at border crossings, loading areas and in severe congestion has been known to deteriorate the combustion and catalytic device performance and to increase the emissions of particulate matter (PM). A conventional diesel engine was coupled to a dynamometer and operated on diesel fuel and neat biodiesel alternately at idle speed and 2% of rated power and at 30% and 100% load at intermediate speed. Exhaust was sampled on fiber filters, from which the content of elemental and organic carbon and polycyclic aromatic hydrocarbons (PAH), including cPAH and benzo[a]pyrene (B[a]P) have been determined. The emissions of cPAH and B[a]P have increased 4-6 times on diesel fuel and by 4-21% on biodiesel during extended idling relative to a short idle and 8 times on diesel fuel and 2-20 times on biodiesel during subsequent operation at full load relative to stabilized operation at full load. The total "excess" cPAH emissions after the transition to full load were on the same order of magnitude as the total "excess" cPAH during extended idling. The absolute levels of PAH, cPAH and B[a]P emissions under all operating conditions were lower on biodiesel compared to diesel fuel. Genotoxicity of organic extracts of particles was analysed by acellular assay with calf thymus DNA (CT-DNA) and was consistently higher for diesel than for biodiesel. The exhaust generated during extended idle and subsequent full load exhibited the highest genotoxicity for both fuels. These two regimes are characterized by significant formation of cPAH as well as other DNA reactive compounds substantially contributing to the total genotoxicity. Oxidative DNA damage by all tested extracts was negligible. (C) 2015 Elsevier Ltd. All rights reserved.

Abstract  Bacterial laccase CueO from Escherichia coli can oxidize polycyclic aromatic hydrocarbons (PAHs); however, its application in the remediation of PAH-contaminated soil mainly suffers from a low oxidation rate and copper dependence. It was reported that a laccase with a higher redox potential tended to have a higher oxidation rate; thus, the present study investigated the oxidation of PAHs using another bacterial laccase CotA from Bacillus subtilis with a higher redox potential (525 mV) than CueO (440 mV). Recombinant CotA was overexpressed in E. coli and partially purified, exhibiting a higher laccase-specific activity than CueO over a broad pH and temperature range. CotA exhibited moderate thermostability at high temperatures. CotA oxidized PAHs in the absence of exogenous copper. Thereby, secondary heavy metal pollution can be avoided, another advantage of CotA over CueO. Moreover, this study also evaluated some unexplained phenomena in our previous study. It was observed that the oxidation of PAHs with bacterial laccases can be promoted by copper. The partially purified bacterial laccase oxidized only two of the 15 tested PAHs, i.e., anthracene and benzo[a]pyrene, indicating the presence of natural redox mediators in crude cell extracts. Overall, the recombinant CotA oxidizes PAHs with high laccase activity and copper independence, indicating that CotA is a better candidate for the remediation of PAHs than CueO. Besides, the findings here provide a better understanding of the oxidation of PAHs using bacterial laccases.

Abstract  Most researches on graphene/polymer composites are focusing on improving the mechanical and electrical properties of polymers at low graphene content instead of paying attention to constructing graphene's macroscopic structures. In current study the homo-telechelic functionalized polyethylene glycols (FPEGs) were tailored with π-orbital-rich groups (namely phenyl, pyrene and di-pyrene) via esterification reactions, which enhanced the interaction between polyethylene glycol (PEG) molecules and chemical reduced graphene oxide (RGO) sheets. The π-π stacking interactions between graphene sheets and π-orbital-rich groups endowed the composite films with enhanced tensile strength and tunable electrical conductivity. The formation of graphene network structure mediated by the FPEGs fillers via π-π stacking non-covalent interactions should account for the experimental results. The experimental investigations were also complemented with theoretical calculation using a density functional theory. Atomic force microscope (AFM), scanning electron microscope (SEM), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), thermal gravimetric analysis (TGA), UV-vis and fluorescence spectroscopy were used to monitor the step-wise preparation of graphene composite films. © 2015 Elsevier Ltd. All rights reserved.

Abstract  An electrochemical method is established in this work for the assay of α-glucosidase activity and the inhibitor screening through one-step displacement reaction, which can be directly used in cell medium. The displacement reaction can be achieved via strong binding of 4-aminophenyl-α-D-glucopyranoside (pAPG)/magnetic nanoparticles (MNPs) to pyrene boric acid (PBA) immobilized on the surface of graphite electrode (GE), compared to that of dopamine (DA)/sliver nanoparticles (AgNPs). Since α-glucosidase can specifically catalyze MNPs/pAPG into MNPs/pAP which has no binding capacity with PBA, the activity of both isolated and membrane bound enzyme can be well evaluated by using this proposed method. Meanwhile, signal amplification can be accomplished via the immobilization of DA at the outer layer of AgNPs, and the accuracy can be strengthened through magnetic separation. Moreover, this method can also be utilized for inhibitor screening not only in the medium containing the enzyme but also in cell medium. With good precision and accuracy, it may be extended to other proteases and their inhibitors as well.

Abstract  In order to distinguish small aromatics preferably, a Nd : YAG Laser was used to supply an excitation laser, which was adjusted to 0.085 J . cm(-2) at 266 nm. Benzene, toluene, naphthalene, phenanthrene, anthracene, pyrene and chrysene were used as the representative of different rings aromatics. The fluorescence emission spectra were researched for each aromatic hydrocarbon and mixtures by Laser induced fluorescence (LIF). Results showed that the rings number determined the fluorescence emission spectra, and the structure with same rings number did not affect the emission fluorescence spectrum ranges. This was due to the fact that the absorption efficiency difference at 266 nm resulted in that the fluorescence intensities of each aromatic hydrocarbon with same rings number were different and the fluorescence intensities difference were more apparently with aromatic ring number increasing. When the absorption efficiency was similar at 266 nm and the concentrations of each aromatic hydrocarbon were same, the fluorescence intensities were increased with aromatic ring number increasing. With aromatic ring number increasing, the fluorescence spectrum and emission peak wavelength were all red-shifted from ultraviolet to visible and the fluorescence spectrum range was also wider as the absorption efficiency was similar. The fluorescence emission spectra from one to four rings could be discriminated in the following wavelengths, 275 to 320 rim, 320 to 375 nm, 375 to 425 rim, 425 to 556 nm, respectively. It can be used for distinguish the type of the polycyclic aromatic hydrocarbons (PAHs) as it exists in single type. As PAHs are usually exist in a variety of different rings number at the same time, the results for each aromatic hydrocarbon may not apply to the aromatic hydrocarbon mixtures. For the aromatic hydrocarbon mixtures, results showed that the one- or two-ring PAHs in mixtures could not be detected by fluorescence as three- or four-ring PAHs existed in mixture. This was caused by radiation energy transfer mechanism, in which the ultraviolet light was lost in mixtures but the fluorescence intensities were increased with the one- or two-ring PAHs adding. When the mixture only contained three- and four-ring PAHs, the fluorescence emission spectrum showed the both characteristics of three- and four-ring PAHs fluorescence. When three- and four-ring PAHs existed in mixtures at the same time, the fluorescence emission spectra were related to each concentration, so the rings number could be discriminated to a certain extent.

Abstract  Several natural compound interfere with microtubules or the actin cytoskeleton. Compounds interfering with the microtubules like Vinca-alkaloids or taxanes, are extensively used for cancer therapy. In contrast, knowledge about pharmacological properties of actin binding drugs is poor and drugs interfering with actin are far from clinical use. Rhizopodin is a natural compound that strongly affects the actin cytoskeleton at nanomolar concentrations. Initial work revealed interesting anti-bacterial and cytotoxic effects, but the cellular effects and pharmacological properties of rhizopodin have not been characterized. We hypothesized that rhizopodin might exert anti-cancer activity. Therefore, the aim of this study was to characterize the cellular and pharmacological effects of rhizopodin in cancer. Effects of rhizopodin demonstrated prominent effects on the actin cytoskeleton as shown in the actin-pyrene assay and by immunostaining of cancer cells. To investigate cellular effects of rhizopodin, we analyzed cell proliferation, cell death induction by propidium iodide exclusion and western blot, as well as migration by impedance measurement using the xCELLligence device in MDA-MB-231 breast cancer and T24 bladder cancer cell lines. Rhizopodin inhibited proliferation and induced cell death of MDA-MB-231 and T24 cells at nanomolar concentrations. PARP cleavage by rhizopodin suggests caspase-dependent cell death induction. Importantly, rhizopodin potently inhibited MDA-MB-231 and T24 cancer cell migration at subtoxic doses where no actin aggregation was observed, indicating a specific underlying signaling of rhizopodin. In summary, our study elucidates rhizopodin as actin-binding natural compound that exerts potent anti-cancer effects. Therefore, our work provides the basis for further in depth characterization of rhizopodin as an antitumoral agent.

Abstract  The aim of this study is to reveal the ability of utilizing different aromatic hydrocarbons (p-hydroxybenzoic acid, naphthalene, phenanthrene, and pyrene) by a halotolerant bacterial strain, Chromohalobacter sp., under saline conditions. The aromatic hydrocarbon degradation pathways were identified. PCR amplification was carried to define the gene zones which codify the dioxygenases of the isolates. The possible gene zones of catechol 1, 2 dioxygenase and protocatechuate 3, and 4 dioxygenase were determined. According to the PCR amplification and enzyme test results Chromohalobacter sp. utilizes aromatic hydrocarbons by the ortho cleavage of the ß-ketoadipate pathway. In this study, it was concluded that this isolate can be used in bioremediation studies of saline environments contaminated with aromatic hydrocarbons. © 2015, Cevkor Vakfi. all rights reserved.

Abstract  A fast and simple modified QuEChERS extraction method was developed for determination of Benzo[a]pyrene (BaP) in 137 traditional (Sangak), semi-industrial (Sangak) and industrial bread samples using spiked calibration curves by GC/MS. Sample preparation includes extraction of BaP into acetone followed by cleanup with dispersive solid phase extraction. The limit of detection and limit of quantification were 0.3 ng/g and 0.5 ng/g, respectively. The values for recoveries and RSD were calculated as 110.5-119.85% and <11.6% respectively. Average concentration of BaP in Sangak bread samples of Shiraz and Tehran was 0.59 and 0.60 ng/g, respectively. 35.5% of samples of breads collected in Tehran were contaminated with BaP at the amount higher than maximum levels regulated in processed cereal-based foods and baby foods by European Commission (1 ng/g). Seventeen percent of samples of breads collected in Shiraz were contaminated with BaP which 13 % of total samples were >1 ng/g. BaP content in all industrial samples was lower than LOQ. Assuming the consumption of bread in Tehran and Shiraz is limited to these kinds of breads, the daily intake of BaP in Tehran and Shiraz population through bread consumption was estimated to be 170.6 and 168.7 ng/day, respectively. This is the first report concerning contamination of bread samples with BaP in Iran.

Abstract  Pyrene derivatives are among the most widely used organic fluorescent photoprobes. Many of them are photosensitizers for hole injection. Pyrenes, however, are mostly UV absorbers, limiting their utility for photonic applications. Nitration of pyrene shifts its absorption to the visible region. Conversely, nitration of pyrene that is already derivatized for covalent labeling, produces mixtures of isomers that are challenging to separate. We present a robust procedure for attaining isomerically pure nitropyrenes. NMR analysis provides unequivocal assignments of the regioisomers and of the structures of the disubstituted nitropyrenes. The added substituents negligibly affect the electronic properties of the nitropyrenes. Photoexcited nitropyrenes undergo efficient triplet formation, making them an attractive choice for triplet sensitizers and photooxidants. Hence, facile and reliable preparation of disubstituted nitropyrenes provides venues for exploring their electronic and photonic utility. Copyright © 2016 Wiley-VCH Verlag GmbH & Co. KGaA.

Abstract  The synthesis of 2-rotaxane (3•TMS-αCD) through a condensation reaction between 3,5-diamino-1,2,4-triazole encapsulated into hexakis(2,3,6-trimethylsilyl) α-cyclodextrin cavity (TMS-αCD) and 1-pyrenecarboxaldehyde is reported. The oxidative coupling of 3•TMS-αCD afforded then pyrene-triazole/TMS-αCD PAMs polyrotaxane (4•TMS-αCD) azomethine polyrotaxane. The optical, electrochemical, morphological, surface-free energies, as well as transport properties of 3•TMS-αCD and its corresponding 4•TMS-αCD polyrotaxane have been investigated and compared with those of the reference polymer pyrene-triazole azomethine. The polyrotaxane is soluble in toluene/dimethylformamide (DMF) 1:1, v/v, mixture and displays useful levels of thermal stability and higher fluorescence quantum yield (ΦPL) in DMF solutions. ΦPL improvement is further reflected in the fluorescence lifetime (τF), significantly longer than that of the starting monomer 3•TMS-αCD (7.8 vs 0.89 ns). In addition, a smoother surface with the smaller grains uniformly distributed on the surface, as well as lower surface-free energy, combined with energy gap (3.32 vs 3.76 eV) represent noticeable advantages of azomethine backbones encapsulation by TMS-αCD. Host-guest complexation of azomethine backbones into TMS-αCD cavities leads to improvement of the solubility and better film-forming ability associated with a smoother surface and lower root-mean-square roughness. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.