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Fluorene
Terms modified by Fluorene Selected AbstractsAssessment of sediment quality of Yangtze River estuary using zebrafish (Danio rerio) embryosENVIRONMENTAL TOXICOLOGY, Issue 3 2010Lingling Wu Abstract Yangtze River estuary is one of the largest estuaries worldwide. In this study, the sediment quality of Yangtze River estuary was evaluated using zebrafish (Danio rerio) embryos. Freshly fertilized zebrafish eggs (2 h after fertilization) were exposed to the whole sediment and its organic phase of extract, respectively. The parameters, including survival rate, abnormality, hatching rate, and heart rate of the zebrafish embryos, were recorded during the 96-h exposure. The results demonstrated that the concentrations of heavy metals (Zn, Cu, Cd, Ni, Cr, and As) and low-molecular weight PAHs (Fluorene) in the sediment of Yangtze River estuary exceeded their corresponding effects range low values. The maximum concentrations of Zn and Fluorene in the sediment samples were 239.6 ,g/g and 45.9 ng/g, respectively. In both whole sediment test and organic extract test, the survival rate and heart rate of zebrafish embryos were reduced, as well as abnormalities and delayed hatching were induced. For example, the highest mortality of the embryos was 39% in the whole sediment exposure. Overall, the occurrence of toxic compounds in the sediment of Yangtze River estuary may have potentially teratogenic effect on biota. The sediment from the upstream of Yangtze River estuary have more observed toxic effects on zebrafish embryos than that form the downstream. Therefore, more attention should be paid to control these pollutants, especially heavy metals in the Yangtze River estuary. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source] Influence of phenanthrene and fluoranthene on the degradation of fluorene and glucose by Sphingomonas sp. strain LB126 in chemostat culturesFEMS MICROBIOLOGY ECOLOGY, Issue 1 2003René van Herwijnen Abstract Since bacteria degrading polycyclic aromatic hydrocarbon compounds (PAHs) in polluted soils are generally exposed to mixtures of PAHs, we examined the influence of simple PAH mixtures on the degradation activity of Sphingomonas sp. strain LB126. Fluorene serves as sole carbon and energy source for the strain LB126 and phenanthrene and fluoranthene are cometabolically degraded by this species. Chemostat cultures of the strain LB126 were used to study a potential inhibiting effect of phenanthrene and fluoranthene on the degradation of fluorene that was previously observed in batch cultures. We also looked at the effect of phenanthrene on the degradation of glucose in a chemostat culture to see if this effect was specific for the PAH-metabolic pathway or for the total metabolism of the strain. The co-substrates were supplied in a 5% to 30% fraction of fluorene. Phenanthrene and fluoranthene had no significant influence on growth. However, fluorene degradation was inhibited by both phenanthrene and fluoranthene. The effect of phenanthrene was about 10 times stronger than the effect of fluoranthene. Nevertheless, more than 95% removal of fluorene took place together with more than 95% removal of either phenanthrene or fluoranthene. The effect of phenanthrene on the strain LB126 could be ascribed to both toxicity and competitive inhibition, but the effect observed at steady state was due to competitive inhibition only. It appeared that the strain LB126 adapts to the toxicity of phenanthrene within five generations. The inhibitory effects observed previously in batch cultures of the strain LB126 should mainly be ascribed to the toxic effect of phenanthrene. [source] Multifunctional Fluorene-Based Oligomers with Novel Spiro-Annulated Triarylamine: Efficient, Stable Deep-Blue Electroluminescence, Good Hole Injection, and Transporting Materials with Very High TgADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Zuoquan Jiang Abstract A series of fluorene-based oligomers with novel spiro-annulated triarylamine structures, namely DFSTPA, TFSTPA, and TFSDTC, are synthesized by a Suzuki cross-coupling reaction. The spiro-configuration molecular structures lead to very high glass transition temperatures (197,253,°C) and weak intermolecular interactions, and consequently the structures retain good morphological stability and high fluorescence quantum efficiencies(0.69,0.98). This molecular design simultaneously solves the spectral stability problems and hole-injection and transport issues for fluorene-based blue-light-emitting materials. Simple double-layer electroluminescence (EL) devices with a configuration of ITO/TFSTPA (device A) or TFSDTC (device B)/ TPBI/LiF/Al, where TFSTPA and TFSDTC serve as hole-transporting blue-light-emitting materials, show a deep-blue emission with a peak around 432,nm, and CIE coordinates of (0.17, 0.12) for TFSTPA and (0.16, 0.07) for TFSDTC, respectively, which are very close to the National Television System Committee (NTSC) standard for blue (0.15, 0.07). The maximum current efficiency/external quantum efficiencies are 1.63,cd A,1/1.6% for device A and 1.91,cd A,1/2.7% for device B, respectively. In addition, a device with the structure ITO/DFSTPA/Alq3/LiF/Al, where DFSTPA acts as both the hole-injection and -transporting material, is shown to achieve a good performance, with a maximum luminance of 14,047,cd m,2, and a maximum current efficiency of 5.56,cd A,1. These values are significantly higher than those of devices based on commonly usedN,N,-di(1-naphthyl)- N,N,-diphenyl-[1,1,-biphenyl]-4,4,-diamine (NPB) as the hole-transporting layer (11,738,cd m,2 and 3.97,cd A,1) under identical device conditions. [source] Exploiting a Dual-Fluorescence Process in Fluorene,Dibenzothiophene- S,S -dioxideCo-Polymers to Give Efficient Single Polymer LEDs with Broadened EmissionADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Simon M. King Abstract A description of the synthesis of random (9,9-dioctylfluorene-2,7-diyl),(dibenzothiophene- S,S -dioxide-3,7-diyl) co-polymers (p(F-S)x) by palladium-catalyzed Suzuki cross-coupling polymerization where the feed ratio of the latter is varied from 2 to 30,mol % (i.e., x,=,2,30) is given. Polymer light emitting devices are fabricated with the configuration indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid)/p(F,S)x/Ba/Al. The device external quantum efficiency increased as the ratio of the S co-monomer was increased, up to a maximum of 1.3% at 100,mA cm,2 for p(F-S)30 and a brightness of 3 770,cd m,2 (at 10,V). The S units impart improved electron injection, more balanced mobilities, and markedly improved device performance compared to poly(9,9-dioctylfluorene) under similar conditions. These co-polymers display broad emission, observed as greenish-white light, which arises from dual fluorescence, viz. both local excited states and charge transfer states. Utilizing dual emission can reduce problems associated with Förster energy transfer from high-energy to-low energy excited states. [source] Hole Injection in a Model Fluorene,Triarylamine CopolymerADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Hon Hang Fong Abstract Recent developments in synthesis and purification have yielded conjugated polymers with hole mobilities exceeding 0.01,cm2 V,1 s,1. Essential to harvesting the potential of these materials in organic light emitting diodes (OLEDs) is the identification of suitable ohmic contacts. Using a model fluorene copolymer that shows high-mobility, non-dispersive hole transport, it is demonstrated that electrodes commonly used as anodes in OLEDs are very poor hole injectors. Injection from Au and indium tin oxide anodes is limited by energy barriers of 0.75 and 0.65,eV, respectively, and the injected current is found to be temperature independent,a prediction that was not reproduced by the leading injection model for disordered organic semiconductors. Injection from a poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) anode, on the other hand, is found to become less efficient with electric field, a behavior which is currently not understood. In thinner poly[(9,9,-dioctylfluorenyl-2,7-diyl)- co -(4,4,-(N -(4- sec -butyl))diphenylamine)] films, which are of relevance to OLEDs, ohmic losses on the PEDOT:PSS layer are found to limit the flow of current. These results illustrate the opportunity to further improve the performance of OLEDs as well as the challenge posed by high mobility conjugated polymers for the design of hole injection layers. [source] The Influence of UV Irradiation on Ketonic Defect Emission in Fluorene-Based Copolymers,ADVANCED FUNCTIONAL MATERIALS, Issue 17 2008Horst Scheiber Abstract The influence of UV irradiation in inert atmosphere on the emission spectrum of fluorenone containing poly[9,9-bis(2-ethyl)hexylfluorene] (PF2/6) has been investigated by means of optical absorption, photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy. It is shown that a substantial reduction of green emission arising from ketonic defect sites can be achieved by irradiation of thin films with UV light. This is found to be accompanied by partial cross-linking of the films. FTIR measurements show no reduction of the C=O stretching mode upon irradiation, and, moreover, the degree of cross-linking does not scale with the relative fluorenone content (0.1, 0.5, and 5%). Therefore, the reduced emission intensity in the green spectral region is rather associated with the occurrence of interruptions in the polymer backbone, which reduce the effective conjugation length and subsequently inhibit the energy transfer onto the ketonic defect sites. The found results enabled us to build organic light emitting devices (OLEDs) that can be structured by selective illumination of the emitting layer with an intense UV light source. This method allows for the fabrication of rather efficient (2000,cd,m,2 at 7,V) two-color OLEDs. [source] Insight into the Role of Oxidation in the Thermally Induced Green Band in Fluorene-Based Systems,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2007R. Grisorio Abstract The causes of the spectral instability of poly[9,9-dioctylfluoren-2,7-diyl-co-2,,7,-spiro(cyclohexane-1,9,-fluorene)] during thermal annealing in air, which leads to a green photoluminescence (PL) emission band, are investigated. The Igreen/Iblue ratio evolution (I,=,intensity) is found to be independent of the amount of monoalkylfluorene defects, despite the fact that their presence might be regarded as a trigger for the radical process leading to polymer degradation in the presence of a trace amount of metal catalyst. Furthermore, the absence of a correlation between the degree of oxidation of the material and the Igreen/Iblue ratio indicates that the spatial disposition of fluorenones formed during the thermal degradation of the material, rather than their amount, is to be strictly related to the Igreen/Iblue ratio. The evidenced formation of fluorenone agglomerates, which could be considered the cause for the consistent increase in the Igreen/Iblue ratio during a thermal oxidation of a polyfluorene, confirms that the radical mechanism can also involve dialkylfluorene systems. Finally, the higher resistance to thermal degradation shown by spirocyclohexane fluorene units with respect to dioctylfluorene ones allows the synthesis of new, spectrally stable, fluorene-based copolymers. [source] Fluorene-Based Oligomers for Highly Efficient and Stable Organic Blue-Light-Emitting DiodesADVANCED MATERIALS, Issue 23 2009Chang-Gua Zhen Highly efficient and stable blue-light-emitting materials consisting of oligofluorenyl blocks and charge transporting segments are synthesized. The external quantum efficiencies of the solution-processed light-emitting diodes were of up to 6.1% and 8.6% for undoped and doped devices, respectively. The exceedingly high efficiency and excellent stability of these devices suggest that these new developed materials are very promising for deep-blue-light OLEDs. [source] Fluorene-based materials and their supramolecular propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2009Robert Abbel Abstract Fluorene-based ,-conjugated polymers and oligomers combine several advantageous properties that make them well-suited candidates for applications in organic optoelectronic devices and chemical sensors. This review highlights strategies to synthesize these materials and to tune their absorption and emission colors. Furthermore, methods to control their supramolecular organization will be discussed. In many cases, a delicate interplay between the chemical structure and the processing conditions are found, resulting in a high sensitivity of both structural features and optical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4215,4233, 2009 [source] Fluorene-based liquid crystalline networks with linearly polarized blue emissionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2007Marta Millaruelo Abstract A series of fluorene-based luminophores containing methacrylic end groups have been prepared and incorporated into uniaxially oriented liquid crystalline films by in situ photopolymerization. Various structural modifications on the 2-(4-cyanophenyl)fluorene core, which include alkyl chains at the 9-position and elongation of the rigid core with one additional phenyl ring, have been investigated to generate emitters with adjusted liquid crystal compatibility, improved luminescence and dichroic properties. Polarized blue-emitting films were produced that had an acceptable photostability, and it was found that the polarization emission was better for samples with low (5%) cross-linker contents. Polarization of the luminescence was favored by the liquid crystalline properties of the luminophore. In addition, the detrimental effect of the alkyl substituent at the fluorene core on the mesomorphism and on the emission polarization can be overcome by lengthening the ,-system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4804,4817, 2007 [source] Synthesis of Polystyrene- block -Poly(methyl methacrylate) with Fluorene at the Junction: Sequential Anionic and Controlled Radical Polymerization from a Single CarbonMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 24 2009Nathan D. Contrella Abstract Polystyrene- block -poly(methyl methacrylate) (PS- b -PMMA) has been synthesized by sequential anionic and reverse atom transfer radical polymerization (ATRP) or a variation of nitroxide mediated polymerization (NMP) from a single initiating site, specifically the 9-carbon on 2,7-dibromofluorene or fluorene. The addition of the second arm (PS) relied on thermal decomposition of 2,2,-azoisobutyronitrile (AIBN) to generate radicals, abstracting the 9-H on the polymer-bound fluorene species to form the initiating radical. Styrene was not present in the reaction mixture when AIBN was decomposed, preventing competition between addition across the monomeric alkene and hydrogen abstraction from the fluorene. After 1,h, styrene was introduced and mediation of the subsequent radical polymerization was achieved by the presence of CuCl2/ligand or TEMPO. Characterization of the diblock copolymers by gel permeation chromatography (GPC) revealed substantial shifts in number average molecular weight () values compared to the anionically prepared PMMA macroinitiator, while polydispersity indices (PDI's) remained relatively low (typically,<,1.5). Characterization by UV detection with GPC (at 310,nm) verified that the diblock polymer is chromophore-bound, which was further verified by UV-vis spectroscopy of the isolated diblock. [source] The Effect of Protonation on the Optical Properties of Conjugated Fluorene,Pyridine CopolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2008Stefan Kappaun Abstract A series of conjugated alternating and statistical copolymers of fluorene and pyridine are synthesized and characterized. The compounds under investigation, namely poly[2,7-(9,9-dihexylfluorenyl)- alt -(2,6-pyridinyl)] and poly[2,7-(9,9-dihexylfluorenyl)- stat -(2,6-pyridinyl)], are prepared by a Suzuki-type cross-coupling reaction starting from commercially available materials utilizing the recently described catalyst trans -bis(dicyclohexylamine) palladiumdiacetate ("DAPCy"). The target compounds are investigated by nuclear magnetic resonance and infrared spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, thermal analysis, UV,Vis absorption spectroscopy, and luminescence measurements in solution and in the solid state. Special emphasis is placed on studying the consequences of protonation on the photophysical properties of the described materials. Achieving a concise microscopic understanding of the effects of protonation on the absorption and luminescence characteristics is crucial for potential applications in, e.g., optical sensors. To that aim, the results of the systematic studies of the photophysical properties are explained by quantum mechanical calculations. [source] White-Light Emission from a Single Polymer with Singlet and Triplet Chromophores on the BackboneMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2006Hongyu Zhen Abstract Summary: A strategy to generate an efficient white-light emission has been developed by mixing fluorescence and phosphorescence emission from a single polymer. Fluorene is used as the blue-emissive component, benzothiadiazole (BT) and the iridium complex [(btp)2Ir(tmd)] are incorporated into a polyfluorene backbone, respectively, as green- and red-emissive chromophores by Suzuki polycondensation. By changing the contents of BT and [(btp)2Ir(tmd)] in the polymer, the electroluminescence spectrum from a single polymer can be adjusted to achieve white-light emission. A white polymeric light-emitting diode (WPLED) with a structure of ITO/PEDOT:PSS/PVK/PFIrR1G03/CsF/Al shows a maximum external quantum efficiency of 3.7% and the maximum luminous efficiency of 3.9 cd,·,A,1 at the current density of 1.6 mA,·,cm,2 with the CIE coordinates of (0.33, 0.34). The maximum luminance of 4,180 cd,·,m,2 is achieved at the current density of 268 mA,·,cm,2 with the CIE coordinates of (0.31, 0.32). The white-light emissions from such polymers are stable in the white-light region at all applied voltages, and the electroluminescence efficiencies decline slightly with the increasing current density, thus indicating that the approach of incorporating singlet and triplet species into the polymer backbone is promising for WPLEDs. Structure of PFIrR1G04 and the EL spectra of its devices under various voltages. Device structure: ITO/PEDOT:PSS/PVK/polymer/CsF/Al. [source] Synthesis of Fluorene and Indenofluorene Compounds: Tandem Palladium-Catalyzed Suzuki Cross-Coupling and Cyclization,ANGEWANDTE CHEMIE, Issue 16 2010Tao-Ping Liu Dr. Fluorene im Visier: Palladiumkatalysierte Tandemreaktionen mit einer C(sp3)-H-Bindungsaktivierung als Schlüsselschritt (siehe Schema; DMA=Dimethylacetamid) führen unter Anellierung in hohen Ausbeuten zu substituierten Fluorenen und Indenofluorenen. Die Methode könnte sich auch für die Synthese anderer cyclischer Produkte sowie für substituierte Oligo- oder Polyfluorene eignen. [source] The surprising sp rotameric structure of 9-methyl-9-pivaloylfluoreneACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2000Cal Y. Meyers Methylation of 9-lithiated ap -9-pivaloylfluorene, (I), as well as pivaloylation of 9-lithiated 9-methylfluorene provided rotationally stable sp -9-methyl-9-pivaloylfluorene, (III), C19H20O, which lies about a crystallographic mirror plane. Fluorene (I) exists exclusively in the ap configuration in solution (NMR) as well as in the crystalline state, reflecting the unfavorable interaction between the tert -butyl and fluorene-ring , electrons in the sp configuration. The existence of (III) exclusively in the sp configuration indicates that, in this case, the interaction between the tert -butyl group and the fluorene-ring , electrons provides relatively more thermodynamic stability than the steric interaction between the tert -butyl and 9-methyl groups (ap configuration). [source] Fluorene and phenanthrene uptake by Pseudomonas putida ATCC 17514: Kinetics and physiological aspectsBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2005Ana C. Rodrigues Abstract Pseudomonas putida ATCC 17514 was used as a model strain to investigate the characteristics of bacterial growth in the presence of solid fluorene and phenanthrene. Despite the lower water-solubility of phenanthrene, P. putida degraded this polycyclic aromatic hydrocarbon (PAH) at a maximum observed rate of 1.4 ± 0.1 mg L,1 h,1, higher than the apparent degradation rate of fluorene, 0.8 ± 0.07 mg L,1 h,1. The role of physiological processes on the biodegradation of these PAHs was analyzed and two different uptake strategies were identified. Zeta potential measurements revealed that phenanthrene-grown cells were slightly more negatively charged (,57.5 ± 4.7 mV) than fluorene-grown cells (,51.6 ± 4.9 mV), but much more negatively charged than glucose-grown cells (,26.8 ± 3.3 mV), suggesting that the PAH substrate induced modifications on the physical properties of bacterial surfaces. Furthermore, protein-to-exopolysaccharide ratios detected during bacterial growth on phenanthrene were typical of biofilms developed under physicochemical stress conditions, caused by the presence of sparingly water-soluble chemicals as the sole carbon and energy source for growth, the maximum value for TP/EPS during growth on phenanthrene (1.9) being lower than the one obtained with fluorene (5.5). Finally, confocal laser microscopy observations using a gfp -labeled derivative strain revealed that, in the presence of phenanthrene, P. putida::gfp cells formed a biofilm on accessible crystal surfaces, whereas in the presence of fluorene the strain grew randomly between the crystal clusters. The results showed that P. putida was able to overcome the lower aqueous solubility of phenanthrene by adhering to the solid PAH throughout the production of extracellular polymeric substances, thus promoting the availability and uptake of such a hydrophobic compound. © 2005 Wiley Periodicals, Inc. [source] ChemInform Abstract: Synthesis of Fluorene and Indenofluorene Compounds: Tandem Palladium-Catalyzed Suzuki Cross-Coupling and Cyclization.CHEMINFORM, Issue 32 2010Tao-Ping Liu Abstract An efficient and widely applicable method to prepare fluorene and indenofluorene derivatives is reported. [source] ChemInform Abstract: Exploiting the Divergent Reactivity of Aryl,Palladium Intermediates for the Rapid Assembly of Fluorene and Phenanthrene Derivatives.CHEMINFORM, Issue 25 2009Ya-Bin Zhao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Transition Metal Complexes with Heterocyclic Analogues of Fluorene.CHEMINFORM, Issue 5 2004Part 1. No abstract is available for this article. [source] Dipolar Compounds Containing Fluorene and a Heteroaromatic Ring as the Conjugating Bridge for High-Performance Dye-Sensitized Solar CellsCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2010Chih-Hsin Chen Dr. Abstract A novel series of dipolar organic dyes containing diarylamine as the electron donor, 2-cyanoacrylic acid as the electron acceptor, and fluorene and a heteroaromatic ring as the conjugating bridge have been developed and characterized. These metal-free dyes exhibited very high molar extinction coefficients in the electronic absorption spectra and have been successfully fabricated as efficient nanocrystalline TiO2 dye-sensitized solar cells (DSSCs). The solar-energy-to-electricity conversion efficiencies of DSSCs ranged from 4.92 to 6.88,%, which reached 68,96,% of a standard device of N719 fabricated and measured under the same conditions. With a TiO2 film thickness of 6,,m, DSSCs based on these dyes had photocurrents surpassing that of the N719-based device. DFT computation results on these dyes also provide detailed structural information in connection with their high cell performance. [source] Asymmetrical Fluorene[2,3- b]benzo[d]thiophene Derivatives: Synthesis, Solid-State Structures, and Application in Solution-Processable Organic Light-Emitting DiodesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Chunyan Du Abstract A series of novel asymmetrical fused compounds containing the backbone of fluorene[2,3- b]benzo[d]thiophene (FBT) were effectively synthesized and fully characterized. Single-crystal X-ray studies demonstrated that the length of the substituent side chains greatly affects the solid-state packing of the obtained fused compounds. DFT, photophysical, and electrochemical studies all showed that the FBTs have large band gaps, low-lying HOMO energy levels, and therefore good stability toward oxidation. Moreover, the substituents strongly influence the fluorescence properties of the resulting FBT derivatives. The di- n -hexyl compound exhibits intense fluorescence in solution with the highest quantum yield of up to 91,%. Solution-processed green phosphorescent organic light-emitting diodes with the di- n -butyl derivative as the host material exhibited a maximum brightness of 14,185,cd,m,2 and a luminescence efficiency of 12,cd,A,1. [source] Comparative in vitro and in vivo genotoxicities of 7H -benzo[c]fluorene, manufactured gas plant residue (MGP), and MGP fractionsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2004Leslie Cizmas Abstract Manufactured gas plant residue (MGP) is a complex mixture of polycyclic aromatic hydrocarbons (PAHs) that is tumorigenic in the lungs of mice. This study compared the relative genotoxicity of 7H -benzo[c]fluorene (BC), a PAH component of MGP, with MGP and MGP fractions in order to assess the contribution of BC to the genotoxicity of MGP. An MGP sample was separated into seven fractions (F1,F7) using silica gel column chromatography with petroleum ether (PE) followed by PE:acetone (99:1 v/v, then 98:2). PAHs were quantified using gas chromatography/mass spectrometry. An aliquot of F2, the fraction with the highest BC concentration and highest weighted mutagenic activity in Salmonella typhimurium strain TA98, was further separated using silica gel thin-layer chromatography with hexane. The first F2 subfraction, sF2-a, was enriched in BC and coeluting compounds and contained 35,000 ppm BC and 216,109 ppm carcinogenic PAHs (cPAHs, the sum of seven PAHs categorized by the U.S. EPA as class B2 carcinogens). The second F2 subfraction, sF2-b, contained a ninefold lower concentration of BC, with 3,900 ppm BC and 45,216 ppm cPAHs. Female ICR mice received topical application of crude MGP, crude MGP spiked with analytical-grade BC, F2, sF2-a, sF2-b, or analytical-grade BC. DNA adduct levels were analyzed by nuclease P1-enhanced 32P-postlabeling. In lung DNA of mice receiving 0.48 or 3.0 mg/mouse, net total RAL × 109 values were F2, 30.8 and 87.2; sF2-a, 24.8 and 106.7; and sF2-b, 19.6 and 151.0, respectively. Mice dosed with 0.10 mg analytical-grade BC (the mass of BC in 3.0 mg sF2-a) exhibited a net total RAL × 109 value of 7.03 in lung DNA. This was equal to approximately 7% of the total RAL × 109 value produced by 3.0 mg sF2-a. Thus, although BC appears to make an appreciable contribution to pulmonary adduct formation, the results suggest that MGP components other than BC play an important role in lung DNA adduct formation following topical MGP administration. Environ. Mol. Mutagen. 43:159,168, 2004. © 2004 Wiley-Liss, Inc. [source] A pyrene-degrading consortium from deep-sea sediment of the West Pacific and its key member Cycloclasticus sp.ENVIRONMENTAL MICROBIOLOGY, Issue 8 2008Summary A pyrene-degrading bacterial consortium was obtained from deep-sea sediments of the Pacific Ocean. The consortium degraded many kinds of polycyclic aromatic hydrocarbons (PAHs), including naphthalene, phenanthrene, pyrene, acenaphthene, fluorene, anthracene, fluoranthene, 2-methylnaphthalene and 2,6-dimethylnaphthalene, but it did not grow with chrysene and benzo[,]pyrene. With methods of plate cultivation and polymerase chain reaction,denaturing gradient gel electrophoresis (PCR-DGGE), 72 bacteria belonging to 22 genera were detected from this consortium. Among the detected bacteria, the following genera frequently occurred: Flavobacterium, Cycloclasticus, Novosphingobium, Halomonas, Achromobacter, Roseovarius and Alcanivorax. The first two genera showed the strongest bands in denaturing gradient gel electrophoresis (DGGE) profiles and appeared in all PAH treatments. By now, only one isolate designated P1 was confirmed to be a pyrene degrader. It was identified to be Cycloclasticus spirillensus (100%). Although P1 can degrade pyrene independently, other bacteria, such as Novosphingobium sp. (Band 14), Halomonas sp. (Band 16) and an unidentified bacterium (Band 35), were involved in pyrene degradation in some way; they persist in the consortium in the test of dilution to extinction if only the consortium was motivated with pyrene. However, the secondary most important member Flavobacterium sp. evaded from the community at high dilutions. As a key member of the consortium, P1 distinguished itself by both cell morphology and carbon source range among the isolates of this genus. Based on intermediate analyses of pyrene degradation, P1 was supposed to take an upper pathway different from that previously reported. Together with the results of obtained genes from P1 homology with those responsible for naphthalene degradation, its degradation to pyrene is supposed to adopt another set of genes unique to presently detected. Summarily, an efficient pyrene-degrading consortium was obtained from the Pacific Ocean sediment, in which Cycloclasticus bacterium played a key role. This is the first report to exploit the diversity of pyrene-degrading bacteria in oceanic environments. [source] Microbiological evaluation of toxicity of three polycyclic aromatic hydrocarbons and their decomposition products formed by advanced oxidation processesENVIRONMENTAL TOXICOLOGY, Issue 3 2003Teresa Jamroz Abstract The toxicity of benzo[a]pyrene, chrysene, and fluorene and their decomposition products formed by advanced oxidation processes (AOPs) was investigated using biotests with Escherichia coli and Vibrio fischeri. The polycyclic aromatic hydrocarbons (PAHs) were not highly toxic to either bacterial strain; the toxicity of their degradation products depended on the method of chemical processing. Inhibition of more than 27% was observed with products formed by oxidation of the PAHs, by AOP methods without hydrogen peroxide. Toxicity as high as 100% was observed after the combined action of hydrogen peroxide and other oxidizing agents. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 187,191, 2003 [source] Predicting survival of grass shrimp (Palaemonetes pugio) exposed to naphthalene, fluorene, and dibenzothiophene,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2008Michael A. Unger Abstract The composition and persistence of dissolved polycyclic aromatic hydrocarbons (PAHs) released to the water column during oil spills are altered by weathering, tidal transport, and addition of dispersants. Conventional toxicity effect metrics, such as the median lethal concentration (LC50), are inaccurate predictors of mortality from all toxicant exposure duration/concentration combinations likely to occur during spills. In contrast, survival models can predict the proportions of animals dying as a consequence of exposures differing in duration and intensity. Extending previous work with ethylnaphthalene, dimethylnaphthalene, and phen-anthrene, survival time models were developed that include exposure duration and concentration to predict time to death for grass shrimp (Palaemonetes pugio). Two additional PAHs (naphthalene and fluorene) and a heterocyclic aromatic hydrocarbon (dibenzothiophene) were evaluated for the present study. Preliminary explorations of these models confirmed that quantitative structure-activity regression models were possible for predicting survival model parameters from compound characteristics. Conventional 48-h LC50s also were calculated for the compounds and combined with published LC50s to predict relative PAH toxicity to P. pugio based on octanol-water partitioning. [source] Effects of eight polycyclic aromatic compounds on the survival and reproduction of the springtail Folsomia fimetaria L. (collembola, isotomidae)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2001Line E. Sverdrup Abstract The effects of eight polycyclic aromatic compounds on the survival and reproduction of the collembolan Folsomia fimetaria L. were investigated in a well-characterized Danish agricultural soil. With the exception of acridine, polycyclic aromatic hydrocarbons (PAHs) and neutral N-, S-, and O-monosubstituted analogues showed similar toxicities to soil collembolans when the results were expressed in relation to total soil concentrations (mg/kg). The estimated concentrations resulting in a 10% reduction of reproductive output (EC10 values) were based on measured initial concentrations and were for acridine 290 mg/kg, carbazole 10 mg/kg, dibenzofuran 19 mg/kg, dibenzothiophene 7.8 mg/kg, fluoranthene 37 mg/kg, fluorene 7.7 mg/kg, phenantrene 23 mg/kg, and pyrene 10 mg/kg. When the EC10 values were converted to soil pore-water concentrations, they showed a highly significant correlation (r2 = 0.71, p < 0.01) to no-observed-effect concentrations for the freshwater crustacean Daphnia magna, as estimated by a quantitative structure activity relation (QSAR) for baseline toxicity (nonpolar narcosis). Only carbazole and acridine were more than two times more toxic (4.9 and 3.1, respectively) than expected from the Daphnia QSAR data. The latter result indicates that the toxicity of the tested substances is close to that expected for compounds with nonpolar narcosis as the mode of action. However, the relatively large uncertainties in the extrapolation method prevent final conclusions from being drawn. [source] Cytochrome P4501A induction potencies of polycyclic aromatic hydrocarbons in a fish hepatoma cell line: Demonstration of additive interactionsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2000Karl Fent Abstract The relative CYP1A induction potencies, determined as ethoxyresorufin- O -deethylase (EROD) activity, and the cytotoxicities of 19 compounds with one to six benzene rings, mixtures of polycyclic aromatic hydrocarbons (PAHs), and contaminated landfill leachates have been determined in the permanent fish hepatoma cell line PLHC-1. No CYP1A induction was observed with benzene, naphthalene, anthracene, acenaphthene, benzo[g,h,i]perylene, and fluorene and low induction was found with fluoranthene and phenanthrene. All other PAHs with three and more benzene rings led to a concentration-related induction of CYP1A, with rebound decreases at high concentrations resulting in bell-shaped concentration,activity curves. Fish-related induction equivalency factors (IEFs) were estimated for all PAHs on the basis of EC50 values of their EROD activities and are reported here for the first time. The following order of decreasing IEFs was found: dibenz[a,h]anthracene > dibenzo[a,i]pyrene > benzo[k]fluoranthene > 3-methylcholanthrene > benzo[a]pyrene > benzo[e]pyrene > chrysene > 7,12-dimethylbenz[a]anthracene > perylene > benz[a]anthracene > pyrene. In contrast to the EROD activity, the immunodetectable protein content determined by ELISA showed a concentration-dependent increase. The interaction of PAHs in mixtures of up to eight individual compounds was additive based on their EROD activities. In landfill leachates, determined induction equivalents (IEQ) were significantly higher than calculated IEQs based on analytical measurements, which indicates additional unknown inducing compounds present in leachates. This study shows that the PLHC-1 cell in vitro system serves as an integrative bioanalytical tool in the ecotoxicological evaluation of aquatic environmental samples contaminated with CYP1A-inducing compounds. [source] An Alternative Approach to Constructing Solution Processable Multifunctional Materials: Their Structure, Properties, and Application in High-Performance Organic Light-Emitting DiodesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Shanghui Ye Abstract A new series of full hydrocarbons, namely 4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(N,N -diphenylaniline) (DTPAFB), N,N,-(4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(4,1-phenylene))bis(N -phenylnaphthalen-1-amine) (DNPAFB), 1,3-bis(9-(4-(9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, and 1,3-bis(9-(4-(3,6-di- tert -butyl-9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, featuring a highly twisted tetrahedral conformation, are designed and synthesized. Organic light-emitting diodes (OLEDs) comprising DNPAFB and DTPAFB as hole transporting layers and tris(quinolin-8-yloxy)aluminum as an emitter are made either by vacuum deposition or by solution processing, and show much higher maximum efficiencies than the commonly used N,N,-di(naphthalen-1-yl)- N,N,-diphenylbiphenyl-4,4,-diamine device (3.6 cd A,1) of 7.0 cd A,1 and 6.9 cd A,1, respectively. In addition, the solution processed blue phosphorescent OLEDs employing the synthesized materials as hosts and iridium (III) bis[(4,6-di-fluorophenyl)-pyridinato-N, C2] picolinate (FIrpic) phosphor as an emitter present exciting results. For example, the DTPAFB device exhibits a brightness of 47 902 cd m,2, a maximum luminescent efficiency of 24.3 cd A,1, and a power efficiency of 13.0 lm W,1. These results show that the devices are among the best solution processable blue phosphorescent OLEDs based on small molecules. Moreover, a new approach to constructing solution processable small molecules is proposed based on rigid and bulky fluorene and carbazole moieties combined in a highly twisted configuration, resulting in excellent solubility as well as chemical miscibility, without the need to introduce any solubilizing group such as an alkyl or alkoxy chain. [source] Influence of phenanthrene and fluoranthene on the degradation of fluorene and glucose by Sphingomonas sp. strain LB126 in chemostat culturesFEMS MICROBIOLOGY ECOLOGY, Issue 1 2003René van Herwijnen Abstract Since bacteria degrading polycyclic aromatic hydrocarbon compounds (PAHs) in polluted soils are generally exposed to mixtures of PAHs, we examined the influence of simple PAH mixtures on the degradation activity of Sphingomonas sp. strain LB126. Fluorene serves as sole carbon and energy source for the strain LB126 and phenanthrene and fluoranthene are cometabolically degraded by this species. Chemostat cultures of the strain LB126 were used to study a potential inhibiting effect of phenanthrene and fluoranthene on the degradation of fluorene that was previously observed in batch cultures. We also looked at the effect of phenanthrene on the degradation of glucose in a chemostat culture to see if this effect was specific for the PAH-metabolic pathway or for the total metabolism of the strain. The co-substrates were supplied in a 5% to 30% fraction of fluorene. Phenanthrene and fluoranthene had no significant influence on growth. However, fluorene degradation was inhibited by both phenanthrene and fluoranthene. The effect of phenanthrene was about 10 times stronger than the effect of fluoranthene. Nevertheless, more than 95% removal of fluorene took place together with more than 95% removal of either phenanthrene or fluoranthene. The effect of phenanthrene on the strain LB126 could be ascribed to both toxicity and competitive inhibition, but the effect observed at steady state was due to competitive inhibition only. It appeared that the strain LB126 adapts to the toxicity of phenanthrene within five generations. The inhibitory effects observed previously in batch cultures of the strain LB126 should mainly be ascribed to the toxic effect of phenanthrene. [source] Water-Soluble Polyfluorenes as an Interfacial Layer Leading to Cathode-Independent High Performance of Organic Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Seung-Hwan Oh Abstract Novel poly[(9,9-bis((6,-(N,N,N -trimethylammonium)hexyl)-2,7-fluorene)- alt -(9,9-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-9-fluorene)) dibromide (WPF-6-oxy-F) and poly[(9,9-bis((6,-(N,N,N -trimethylammonium)hexyl)-2,7-fluorene)- alt -(9,9-bis(2-(2-methoxyethoxy)ethyl)-fluorene)] dibromide (WPF-oxy-F) compounds are developed and the use of these water-soluble polymers as an interfacial layer for low-cost poly(3-hexylthiophene):phenyl-C61 butyric acid methyl ester (P3HT:PCBM) organic solar cells (OSCs) is investigated. When WPF-oxy-F or WPF-6-oxy-F is simply inserted between the active layer and the cathode as an interfacial dipole layer by spin-coating water-soluble polyfluorenes, the open-circuit voltage (Voc), fill factor (FF), and power-conversion efficiency (PCE) of photovoltaic cells with high work-function metal cathodes, such as Al, Ag, Au, and Cu, dramatically increases. For example, when WPF-6-oxy-F is used with Al, Ag, Au, or Cu, regardless of the work-function of the metal cathode, the Voc is 0.64, 0.64, 0.58, and 0.63,V, respectively, approaching the original value of the P3HT:PCBM system because of the formation of large interfacial dipoles through a reduction of the metal work-function. In particular, introducing WPF-6-oxy-F into a low-cost Cu cathode dramatically enhanced the device efficiency from 0.8% to 3.36%. [source] | ||||||||||||||||||||||||||||