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Background: Microorganisms play an important role in reducing harmful substances in flue-cured tobacco. Numerous studies have been conducted to degrade nicotine by microorganisms. Objectives: The present research deals with the isolation of a potent bacterial strain able to efficiently degrade nicotine and tobacco-specific nitrosamines (TSNAs) in flue-cured tobacco. Material and Methods: Bacterial strain J54, capable of efficiently degrading nicotine and tobacco-specific nitrosamines (TSNAs), was isolated from tobacco leaves and identified. The strain J54 can use nicotine as the sole carbon and nitrogen source and could effectively degrade nicotine while growing in a nicotine isolation medium (NIM) medium. Results: Compared with the control (CK), the total TSNAs content in the tobacco flue-cured eaves after being sprayed with a solution of the J54 strain was found to decrease by 26.22%. Therein, the degradation rates of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N’-nitrosonornicotine (NNN), N’-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) were 24.01%, 26.27%, 28.6%, and 1.83%, respectively. Conclusions: Bacterial strain J54, was isolated from tobacco leaves and identified as a bacterium, which is similar to Bacillus altitudinis based on its morphological and biochemical characteristics and by phylogenetic analysis based on 16S rRNA gene sequences. To our knowledge, this is the first report of the isolation and characterization of a Bacillus sp. strain that can efficiently degrade nicotine and TSNAs. The findings pave the way for the application of new biotechnologies for the degradation of nicotine and TSNAs by microorganisms.

Three hole transport materials, FIPN-p-PCz, FIPN-p-TPA and FIPN-DPCz, incorporating fluorene/indole core with carbazole or triphenylamine unit were synthesized and fully characterized. The photophysical properties, thermal properties and electrochemical properties of these three compounds were fully investigated. The FIPN-based hole transport materials show high thermal stability (Td > 420 °C) and appropriate highest occupied molecular orbital (HOMO) level (∼-5.2 eV). Green phosphorescent organic light-emitting diodes (PhOLEDs) using these FIPN-based derivatives were fabricated to investigate the device performance, compared with NPB as the reference hole transport material. It turned out that the devices using these three compounds exhibited superior performance than that of the NPB-based PhOLED device. Especially, the FIPN-p-PCz based device showed outstanding electroluminescence performance with the maximum current efficiency and external quantum efficiency of 53.7 cd/A and 17.3%, respectively, which was almost twice that of the NPB based device.

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Janus graphene stacks as artificial graphite allow the reversible intercalation of sodium ions., Sodium, in contrast to other metals, cannot intercalate in graphite, hindering the use of this cheap, abundant element in rechargeable batteries. Here, we report a nanometric graphite-like anode for Na+ storage, formed by stacked graphene sheets functionalized only on one side, termed Janus graphene. The asymmetric functionalization allows reversible intercalation of Na+, as monitored by operando Raman spectroelectrochemistry and visualized by imaging ellipsometry. Our Janus graphene has uniform pore size, controllable functionalization density, and few edges; it can store Na+ differently from graphite and stacked graphene. Density functional theory calculations demonstrate that Na+ preferably rests close to -NH2 group forming synergic ionic bonds to graphene, making the interaction process energetically favorable. The estimated sodium storage up to C6.9Na is comparable to graphite for standard lithium ion batteries. Given such encouraging Na+ reversible intercalation behavior, our approach provides a way to design carbon-based materials for sodium ion batteries.

The electrochemical exfoliation of graphite is one of the cheapest and most tunable industrial techniques to produce graphene nanosheets with a tunable degree of oxidation and solubility. Anodic oxidation allows high-yield production of electrochemically exfoliated graphene oxide (EGO) in either acid or salt solutions, with the key role played by ions electrochemically driven in between the graphene sheets. This chemical intercalation is followed by a mesoscale mechanical exfoliation process, which is key for the high yield of the process, but which is still poorly understood. In this work, we use Raman spectroscopy to simultaneously monitor the intercalation and oxidation processes taking place on the surface of highly ordered pyrolytic graphite (HOPG) during electrochemical exfoliation. The mechanism of EGO formation in either acidic (0.5 M H2SO4) or neutral (0.5 M Li2SO4) electrolytes through blistering and cracking steps is discussed and described. This process is also compared to the non-destructive intercalation of graphite in an organic electrolyte (1 M NaClO4 in acetonitrile). The results obtained show how high exfoliation yield and low defectivity can be achieved by the combination of efficient, non-destructive intercalation followed by chemical decomposition of the intercalants and gas production.

Lithium-sulfur (Li-S) batteries are considered one of the most promising energy storage technologies, possibly replacing the state-of-the-art lithium-ion (Li-ion) batteries owing to their high energy density, low cost, and eco-compatibility. However, the migration of high-order lithium polysulfides (LiPs) to the lithium surface and the sluggish electrochemical kinetics pose challenges to their commercialization. The interactions between the cathode and LiPs can be enhanced by the doping of the carbon host with heteroatoms, however with relatively low doping content (

The electrochemical exfoliation of graphite is one of the cheapest and most tunable industrial techniques to produce graphene nanosheets with a tunable degree of oxidation and solubility. Anodic oxidation allows high-yield production of electrochemically exfoliated graphene oxide (EGO) in either acid or salt solutions, with the key role played by ions electrochemically driven in between the graphene sheets. This chemical intercalation is followed by a mesoscale mechanical exfoliation process, which is key for the high yield of the process, but which is still poorly understood. In this work, we use Raman spectroscopy to simultaneously monitor the intercalation and oxidation processes taking place on the surface of highly ordered pyrolytic graphite (HOPG) during electrochemical exfoliation. The mechanism of EGO formation in either acidic (0.5 M H

Energy-storage materials can be assembled directly on the electrodes of a battery using electrochemical methods, this allowing sequential deposition, high structural control, and low cost. Here, a two-step approach combining electrophoretic deposition (EPD) and cathodic electrodeposition (CED) is demonstrated to fabricate multilayer hierarchical electrodes of reduced graphene oxide (rGO) and mixed transition metal sulfides (NiCoMnSx). The process is performed directly on conductive electrodes applying a small electric bias to electro-deposit rGO and NiCoMnSx in alternated cycles, yielding an ideal porous network and a continuous path for transport of ions and electrons. A fully rechargeable alkaline battery (RAB) assembled with such electrodes gives maximum energy density of 97.2 Wh kg−1 and maximum power density of 3.1 kW kg−1, calculated on the total mass of active materials, and outstanding cycling stability (retention 72% after 7000 charge/discharge cycles at 10 A g−1). When the total electrode mass of the cell is considered, the authors achieve an unprecedented gravimetric energy density of 68.5 Wh kg−1, sevenfold higher than that of typical commercial supercapacitors, higher than that of Ni/Cd or lead–acid Batteries and similar to Ni–MH Batteries. The approach can be used to assemble multilayer composite structures on arbitrary electrode shapes.

We report two bipolar host materials bearing hole-transport benzofurocarbazole/indenocarbazole cores and an electron-transport benzimidazole moiety for red phosphorescence organic light emitting devices (PhOLEDs). The two novel host materials exhibited excellent physical properties with high thermal stabilities, appropriate HOMO-LUMO energy levels and balanced charge transport. Both of them were applied to fabricate red PhOLEDs as promising host materials, and 7,7-dimethyl-5-(4′-(1-phenyl-1 H -benzo[ d ]imidazol-2-yl)-[1,1′-biphenyl]-4-yl)-5,7-dihydroindeno[2,1- b ]carbazole ( ICBI ) based device demonstrated outstanding electroluminescence performance with the maximum current efficiency, power efficiency and external quantum efficiency of 33.0 cd/A, 13.9 lm/W and 18.9%, respectively.

We describe a nanocomposite material for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH), a coenzyme involved in redox reactions of all living cells and in the detection of many organic species by electrochemical biosensors. The composite is made of nanosheets of electrochemically exfoliated graphene oxide (EGO) covalently functionalized with dopamine (DP) molecules. The EGODP material finally obtained is rich of 1,2-dihydroxyphenyl moieties and is able to detect NADH at a particular low potential value with higher sensitivity with respect to pristine EGO. To study the effectiveness of 1,2-dihydroxyphenyl moieties in inducing electrocatalytic oxidation of NADH, we combined standard voltammetric techniques with UV–Vis absorption spectroelectrochemistry, which allowed us to measure the variations in composition occurring at the electrode|solution interface, i.e. to measure the consumption rate of NADH. Spectroelectrochemical tests performed by polarising the electrode at a fixed potential value were finally used to compare the performance of EGODP with both EGO and EGO-DP blend (MIX) for the detection of NADH. The covalently functionalized EGO (EGODP) shows sensitivity to NADH up to 300 M−1, around 180 % and 140 % better than either pristine EGO or MIX, respectively., Spanish Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDERUE), Ministerio de Ciencia, Innovación y Universidades (RED2018-102412-T) and Junta de Castilla y León (Grant BU297P18).

Wafer surface defect detection plays an important role in product yield improvement. Particles are the main source in the majority of defects on wafer. We calculate and analyze the scattering field around the particles on the un-patterned wafer surface by light scattering method. A model was built to calculate an isolated particle based on Mie theory firstly, and another model was built to calculate particle scattering field on a smooth wafer surface based on Bidirectional Reflectance Distribution Function (BRDF). We simulated the scattering field with different parameters set: incidence angle, polarization state and scattering angle channel. The results verify the feasibility of our method to calculate the scattering field.

We describe a fast and versatile method to functionalize high-quality graphene with organic molecules by exploiting the synergistic effect of supramolecular and covalent chemistry. With this goal, we designed and synthesized molecules comprising a long aliphatic chain and an aryl diazonium salt. Thanks to the long chain, these molecules physisorb from solution onto CVD graphene or bulk graphite, self-assembling in an ordered monolayer. The sample is successively transferred into an aqueous electrolyte, to block any reorganization or desorption of the monolayer. An electrochemical impulse is used to transform the diazonium group into a radical capable of grafting covalently to the substrate and transforming the physisorption into a covalent chemisorption. During covalent grafting in water, the molecules retain the ordered packing formed upon self assembly. Our two-step approach is characterized by the independent control over the processes of immobilization of molecules on the substrate and their covalent tethering, enabling fast (t < 10 s) covalent functionalization of graphene. This strategy is highly versatile and works with many carbon-based materials including graphene deposited on silicon, plastic, and quartz as well as highly oriented pyrolytic graphite.

Three novel molecules were designed and synthesized based on a known compound 9,10-di(naphthalen-2-yl)anthracene (MADN). To broaden the π-conjugated system, three units with different electronegativity were introduced and connected to the C-2 position of MADN by vinyl unit. The Suzuki reaction, the Wittig reaction, and the Heck reaction were employed to synthesize these compounds. MADN is a well-known anthracene derivative which has been widely used as blue emitter. All these results indicate that these novel MADN derivatives could be some kind of potential materials for OLEDs.

Major breakthroughs in batteries would require the development of new composite electrode materials, with a precisely controlled nanoscale architecture. However, composites used for energy storage are typically a disordered bulk mixture of different materials, or simple coatings of one material onto another. We demonstrate here a new technique to create complex hierarchical electrodes made of multilayers of vertically aligned nanowalls of hematite (Fe2O3) alternated with horizontal spacers of reduced graphene oxide (RGO), all deposited on a 3D, conductive graphene foam. The RGO nanosheets act as porous spacers, current collectors and protection against delamination of the hematite. The multilayer composite, formed by up to 7 different layers, can be used with no further processing as an anode in Li-ion batteries, with a specific capacity of up to 1175 A h cm(-2) and a capacity retention of 84% after 1000 cycles. Our coating strategy gives improved cyclability and rate capacity compared to conventional bulk materials. Our production method is ideally suited to assemble an arbitrary number of organic-inorganic materials in an arbitrary number of layers.

We used soluble graphene derivatives to fabricate gas barrier coatings on the surface of several industrially relevant commodity polymers. The coatings are prepared using electrochemically exfoliated graphene oxide, featuring both monoatomic thickness and micron-scale lateral size, showing better gas barrier performance as compared to films of commercial graphene products. A 74% decrease of oxygen transmission rate is found using loadings as low as 0.4 wt. % (0.2 vol. %). The coating process is performed using a combination of solution processing, filtering, and transfer. It is a robust and versatile approach, working with different transfer processes, different starting graphite materials and a wide range of well-known polymeric substrates: poly(ethylene terephthalate), poly(lactic acid), poly(hexamethylene adipamide), poly(propylene), and poly(vinyl chloride). The use of 2D sheets as surface coatings instead of bulk additives overcomes common issues related to dispersion of graphene in a polymer matrix, and gives a clear advantage in preserving the mechanical properties of the bulk polymer. Furthermore, it is a scalable approach able to significantly improve the barrier properties of polymeric films for large-scale applications.

We describe the production of graphene-based composites for energy storage, obtained by a combination of electrochemical and solution processing techniques. Electrochemically exfoliated graphene oxide sheets (EGO) are produced using an original setup that allows fast expansion of graphite flakes and efficient exfoliation of expanded graphite via an electrochemical route. The sheets are deposited on a sacrificial nickel foam together with an iron hydroxide colloidal precursor. Calcination treatment simultaneously renders the EGO foam conductive and transforms Fe(OH)3 into hematite (α-Fe2O3), yielding a nanoporous Fe2O3 layer on the surface of the mesoporous EGO foam, creating an ideal structure for lithium storage. The obtained graphene/metal oxide hybrid is a continuous, electrically conductive three-dimensional (3D) composite featuring a hierarchical meso–nano porous structure. A systematic study of these composites, varying the Fe2O3:EGO ratio, is then performed to maximize their performance as nanostructured electrodes in standard coin cell batteries.

The electron-accepting [1,2,4]triazolo[1,5-a]pyridine (TP) moiety was introduced to build bipolar host materials for the first time, and two host materials based on this TP acceptor and carbazole donor, namely, 9,9′-(2-([1,2,4]triazolo[1,5-a]pyridin-2-yl)-1,3-phenylene)bis(9H-carbazole) (o-CzTP) and 9,9′-(5-([1,2,4]triazolo[1,5-a]pyridin-2-yl)-1,3-phenylene)bis(9H-carbazole) (m-CzTP), were designed and synthesized. These two TP-based host materials possess a high triplet energy (>2.9 eV) and appropriate highest occupied molecular orbital/lowest unoccupied molecular orbital levels as well as the bipolar transporting feature, which permits their applicability as universal host materials in multicolor phosphorescent organic light-emitting devices (PhOLEDs). Blue, green, and red PhOLEDs based on o-CzTP and m-CzTP with the same device configuration all show high efficiencies and low efficiency roll-off. The devices hosted by o-CzTP exhibit maximum external quantum efficiencies (ηext) of 27.1, 25.0, and 15.8% f...

In this study we describe a simple and fast procedure for the covalent functionalization of pristine graphene with a pyrene-terminated alkylazide, transformed in a highly reactive radical by thermal activation. The functionalized graphene sheets showed enhanced dispersibility in organic solvents compared to the pristine ones, thus enhancing their solution processability and compatibility with solvents or polymers. The relative improvement of solubility estimated form the absorption spectra was approximate to 60% in CHCl3 and approximate to 1200% in THF. The obtained materials were characterized by optical absorption spectroscopy, photoemission spectroscopy, infrared spectroscopy and X-rays photoelectron spectroscopy. The presence of the pyrene photoemitting chromophore in the grafting unit allowed to monitor the successful grafting and to confirm the effectiveness of the alkylazide to improve graphene solubility even when present in small amounts on the graphene surface.

Two host heterocyclic compounds 5-(dibenzo[b,d]furan-4-yl)-1-(4,6-diphenyl-1,3,5-triazin-2-yl)-1H-indole (FITRZ) and 5-(dibenzo[b,d]thiophen-4-yl)-1-(4,6-diphenyl-1,3,5-triazin-2-yl)-1H-indole (TITRZ) were synthesized by C N coupling reaction of triazine and dibenzothiophene/dibenzofuran moiety with a 1,5-bridged indole unit. Their photo-physical, thermal and electrochemical properties were fully explored, and the results indicate that both of them are promising phosphorescent host materials for green and red PhOLED devices with low on-set potentials. For example, the green PHOLED based on TITRZ showed the maximum current and external quantum efficiency up to 85.9 cd/A and 23.7%. Meanwhile, the red PhOLED based on FITRZ yielded the maximum current and external quantum efficiency of 41.3 cd/A and 18.8% with a turn-on voltage of 3.0 V.

In this paper, three novel bipolar host materials, 9,9′-Diphenyl-6-(4-pyridinyl)-3,3′-bicarbazole(BCz4Py), 9,9′-Diphenyl-6-(3-pyridinyl)-3,3′-bicarbazole(BCz3Py) and 9,9′-Diphenyl-6-(5-pyrimidinyl)-3,3′-bicarbazole(BCz5Pm), were synthesized by incorporation of bicarbazole as donor with pyridine/pyridimide based N-hexahydroxy nitric heterocycle as acceptor units. The photophysical, thermal and electrochemical properties of these three materials were fully investigated. These compounds all exhibited superior thermal stability with high glass-transition temperature (Tg > 130 °C) and decomposition temperature (Td > 400 °C). Appropriate HOMO (highest occupied molecular orbitial) -LUMO (lowest unoccupied molecular orbital) levels and triplet energy (2.74–2.75 eV) of these compounds make them suitable hosts for green iridium pohosphor Ir(ppy)3 in phosphorescent organic light emitting devices (PhOLEDs). Among them, the BCz3Py hosted device exhibited outstanding performance with maximum external quantum efficiency (EQE) of 14.9%, maximum current efficiency (CE) of 49.9 cd/A, and maximum power efficiency (PE) of 29.1 lm/W, suggesting that BCz3Py is a promising bipolar material for high-efficiency green PhOLEDs.

With the aim of learning more about functional bacterial communities in the tobacco rhizosphere and phyllosphere, a total of 96 nicotine-degrading (ND) bacterial strains isolated using nicotine as the sole carbon source—56 from the rhizosphere and 40 from the phyllosphere—were quantified and analyzed phylogenetically. The ND efficiency of 19 phyllosphere strains (47.5 %) and 39 rhizosphere strains (69.6 %) exceeded 90 %. Patterns of phylogenetic relationships based on 16S rRNA gene sequences revealed a high heterogeneity of community composition and suggested the existence of microenvironment-specific communities. The phyllospheric ND bacterial community was distributed over ten genera, of which Pseudomonas spp. was the dominant population. However, the rhizospheric ND bacterial community was composed of six genera, of which Arthrobacter spp. was the major group. This is the first report of members of genera Massilia, Erwinia, Brevundimonas and Paenibacillus capable of degrading nicotine. Diversity indices were calculated provisionally using sequence data obtained from each ND bacterial library. The species richness, diversity and dominance index of the ND bacterial community of the phyllosphere were higher than that of rhizosphere community, while the evenness index of the phyllopheric community was lower compared to rhizospheric ND bacteria. Metabolic intermediate detection showed that the Pseudomonads isolates possessed all four proposed metabolic pathways of nicotine degradation while the Arthrobacter strains all had only one pyridine pathway. These results greatly enhance our knowledge of the diversity of ND bacteria and demonstrate that the tobacco-associated micro-environment contain diverse and novel ND bacteria, which might be a valuable biotechnological resource for biodegradation of nicotine.

We demonstrate a facile, scalable and tunable method to produce a composite material based on graphene multilayers and Fe2O3, combining the good conductivity and 2D layered structure of the former and the lithium storage capacity of the latter. The composite was obtained directly from bulk graphite, exploiting the fast electrochemical intercalation of tetrachloroferrate (III) anions (FeCl4−) and nitromethane molecules between the graphene sheets. Then, irradiation with microwaves triggered the simultaneous exfoliation of graphite and its functionalization with Fe2O3 nanocrystals, produced by the thermal hydrolysis of the FeCl4−. This process was monitored in real time using thermal gravimetry and mass spectrometry. X-rays diffraction, Raman spectroscopy, scanning electron and transmission microscopies confirmed the final structure of the composite formed by conductive 2D nanosheets coated by Fe2O3 crystals, featuring both high crystallinity and nanometric size. The composite could be used directly as an anode in Li-ion batteries, demonstrating the viability of this approach for high yield and scalable production of graphene/metal oxide composites.

Trichoderma is an important biocontrol agent that produces metabolites harmful to nematodes. We investigated the volatile organic compounds (VOCs) of Trichoderma sp. YMF 1.00416 and examined their abilities to kill nematodes. Chemical investigations of the VOCs from this strain led to the isolation and identification of three metabolites: a new compound, 1β-vinylcyclopentane-1α,3α-diol (1) and two known metabolites, 6-pentyl-2H-pyran-2-one (2) and 4-(2-hydroxyethyl)phenol (3). Nematicidal activity assays showed that compound 2 was nematicidal, and killed > 85% of Panagrellus redivivus, Caenorhabditis elegans, and Bursaphelenchus xylophilus in 48 h at 200 mg/L in a 2 mL vial. Our results will help identify new nematicides.

Proteases Bace16 and Bae16, an alkaline serine protease and a neutral protease, respectively, in the nematocidal bacterium Bacillus nematocida B16, have been identified as two key virulence factors and shown to have remarkable nematotoxic activities against the free-living nematode Panagrellus redivius and the plant parasite nematode Bursaphelenchus xylophilus. To facilitate the successful biological control application of this organism in the field, we genetically altered the strain B. nematocida B16 and optimized its growth condition to overexpress these two pathogenic proteases. The recombinant integration vectors of pAX01-Bace16 and pAX01-Bae16 for overexpressing the two proteases were constructed and successfully transformed into competent cells of the bacterium B. nematocida B16. The optimal induction condition for overexpressing Bace16 is 2% xylose at 37°C for 48 h. Our analyses showed that the proteolytic activity and nematocidal activity of the strain overexpressing Bace16 increased by about 62 and 80%, respectively, over the wild-type strain. However, our tested induction conditions could not significantly improve either the proteolytic activity or the nematocidal activity of the Bae16 overexpression mutant.

A new series of benzo[k]fluoranthene derivatives incorporating a diarylamine group have been synthesized and characterized. These compounds show high thermal stability with glass transition temperatures in the range of 162−205 °C. Two-layer electroluminescent devices employing them as the hole-transporting layer and light-emitting layer achieved efficient green emission under low driving voltage. A further optimized three-layer device based on one of these compounds, 3-(1-naphthylphenylamino)-7,12-diphenylbenzo[k]fluoranthene (PNDPBF), exhibited a maximum current efficiency of 10.2 cd/A (6.7 lm/W at 4.70 V). Nonlinear optical properties of these molecules were also investigated by measuring their two-photon excited fluorescence.

A nicotine-sensitive mutant was generated from the nicotine-degrading bacterium, Pseudomonas putida strain J5, by mini-Tn5 transposon mutagenesis. This mutant was unable to grow with nicotine as the sole carbon source but could grow with glucose. Sequence analysis showed that the Tn5 transposon inserted at the site of the ketopantoate hydroxymethyltransferase gene (panB), which had 54% identity to PanB in Escherichia coli K-12. In-frame deletion of the panB gene abolished the nicotine-degrading ability of strain J5, while complementation with panB from P putida J5 and E. coli K-12 restored the degrading activity of the mutant to the wild-type level. These results suggest that ketopantoate hydroxymethyltransferase is a crucial enzyme in nicotine metabolism in P putida J5. (C) 2009 Elsevier Ltd. All rights reserved.

Efficient orange-red phosphorescent organic light-emitting devices (PHOLED) with various doping concentrations of benzotriazole–iridium complex [(TBT)2Ir(acac)] (bis[4-(2H-benzotriazol-2-yl)-N,Ndiphenyl-aniline-N 1 ,C 3 ] iridium acetylacetonate) in 4,4 � -N,N � -di(carbazolyl) biphenyl (CBP) host were fabricated. The sterically hindered iridium ligands alleviate self-quenching of the phosphorescence at high doping levels. Under the optimal doping concentration of 20 wt.%, the maximum external quantum efficiency (EQE), luminance and power yield reach 9.06%, 15.81 cd/A and 13.8 lm/W, respectively. Increasing the doping concentration from 5% to 30 wt.% significantly decreases the driving voltage. The driving voltage of 30% (TBT)2Ir(acac) doped device is only 3.16 V at 1 mA/cm2 with power yield of 13.32 lm/W.

An aerobic bacterial strain N7 capable of effectively degrading nicotine was isolated from the rhizosphere of tobacco in Yunnan, China. This strain was identified asEnsifer sp. based on morphology, physiological characteristics, and 16S rDNA sequence analysis. The optimum nicotine concentration for the growth of strain N7 was 2.0 g/l. There was no more nicotine detected in the medium containing 2.0 g nicotine/l after N7 growth for 24 h and less than16.3% of the nicotine in a medium containing 4.0 g nicotine/l after N7 growth for 48 h. There was a statistically significant linear relationship between nicotine degradation and biomass of strain N7. When a N7 cell suspension (108 CFU/ml) was applied to tobacco leaves, the nicotine concentration was decreased by 16.0%. These data suggest that the novel strain N7 ofEnsifer may be useful for nicotine biodegradation.

An aerobic bacterial strain J5 capable of effectively degrading nicotine was isolated from the rhizosphere of tobacco in Yunnan, China. This strain was identified asPseudomonas putida based on morphology, physiological characteristics, and 16S rDNA sequence analysis. The optimum nicotine concentration for the growth of strain J5 was 2.0 g/l. There was no more nicotine detected in the medium containing 3.0 g of nicotine/l after J5 growth for 24 h and less than 0.2% of the nicotine in a medium containing 4.0 g of nicotine/l after J5 growth for 48 h. There was a statistically significant linear relationship between nicotine degradation and biomass of strain J5. When a J5 cell suspension (108 CFU/ml) was applied to tobacco leaves, the nicotine concentration was decreased by 11.7%. These data suggest that the novel strain J5 ofP. putida may be useful for nicotine biodegradation.

The complete genome sequence of a novel dsRNA virus isolated from Rhizoctonia fumigata AG-Ba isolate C-314 Baishi (designated as Rhizoctonia fumigata virus 1, RfV1) was determined. The RfV1 genome was 9,907 bp in length and contained two open reading frames (ORFs). ORF1 potentially coded for a 198.10-kDa protein (P1). P1 shared low but significant amino acid sequence similarity to the putative protein encoded by Lentinula edodes mycovirus (LeV) ORF1. P1 contained a NUDIX domain, which was also present in the putative proteins encoded by the ORF1s of LeV and Phlebiopsis gigantea large virus 1 (PgLV-1). ORF2 potentially coded for a 146.72-kDa protein (P2) that contained the conserved motifs of the RNA-dependent RNA polymerase (RdRp). ORF1 and ORF2 were overlapping, and it was predicted that ORF2 could be translated as a fusion with ORF1 via a ribosomal -1 frameshifting mechanism. Phylogenetic analysis indicated that RfV1 clustered with PgLV-1, LeV and Rosellinia necatrix megabirnavirus 1 (RnMBV1) in a separate clade independent of other virus genera. We propose that RfV1, along with PgLV-1 and LeV, should be grouped into a new viral genus related to the family Megabirnaviridae. This is the first report of the full-length genome sequence of a novel mycovirus isolated from R. fumigata.

Pseudomonas putida J5 is an efficient nicotine-degrading bacterial strain isolated from the tobacco rhizosphere. We successfully performed a comprehensive whole-genome analysis of nicotine metabolism-associated genes by Tn5 transposon mutagenesis in P. putida J5. A total of 18 mutants with unique insertions screened from 16,324 Tn5-transformants failed to use nicotine as the sole carbon source. Flanking sequences of the Tn5 transposon were cloned with a shotgun method from all of the nicotine-growth-deficient mutants. The potentially essential products of mutated gene were classified as follows: oxidoreductases, protein and metal transport systems, proteases and peptidases, transcriptional and translational regulators, and unknown proteins. Bioinformatic analysis of the Tn5 insertion sites indicated that the nicotine metabolic genes were separated and widely distributed in the genome. One of the mutants, M2022, was a Tn5 insert into a gene encoding a homolog of 6-hydroxy-l-nicotine oxidase, the second enzyme of nicotine metabolism in Arthrobacter nicotinovorans. Genetic and biochemical analysis confirmed that three open reading frames (ORFs) from an approximately 13-kb fragment recovered from the mutant M2022 were responsible for the transformation of nicotine to 3-succinoyl-pyridine via pseudooxynicotine and 3-succinoyl semialdehyde-pyridine, the first three steps of nicotine degradation. Further research on these mutants and the Tn5-inserted genes will help us characterize nicotine metabolic processes in P. putida J5.

The different exfoliation routes of graphite to produce graphene by sonication in solvent, chemical oxidation and electrochemical oxidation are compared. The exfoliation process and roughening of a fl at graphite substrate is directly visualized at the nanoscale by scanning probe and electron microscopy. The etching damage in graphite and the properties of the exfoliated sheets are compared by Raman spectroscopy and X-ray diffraction analysis. The results show the trade-off between exfoliation speed and preservation of graphene quality. A key step to achieve effi cient exfoliation is to couple gas production and mechanical exfoliation on a macroscale with non-covalent exfoliation and preservation of graphene properties on a molecular scale.

Proteases Bace16 and Bae16, an alkaline serine protease and a neutral protease, respectively, in the nematocidal bacterium Bacillus nematocida B16, have been identified as two key virulence factors and shown to have remarkable nematotoxic activities against the free-living nematode Panagrellus redivius and the plant parasite nematode Bursaphelenchus xylophilus. To facilitate the successful biological control application of this organism in the field, we genetically altered the strain B. nematocida B16 and optimized its growth condition to overexpress these two pathogenic proteases. The recombinant integration vectors of pAX01-Bace16 and pAX01-Bae16 for overexpressing the two proteases were constructed and successfully transformed into competent cells of the bacterium B. nematocida B16. The optimal induction condition for overexpressing Bace16 is 2% xylose at 37°C for 48 h. Our analyses showed that the proteolytic activity and nematocidal activity of the strain overexpressing Bace16 increased by about 62 and 80%, respectively, over the wild-type strain. However, our tested induction conditions could not significantly improve either the proteolytic activity or the nematocidal activity of the Bae16 overexpression mutant.