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[en] PCN congeners were analyzed in marine and riverine sediments of the Laizhou Bay area, North China. Concentrations of PCNs ranged from 0.12 to 5.1 ng g-1 dry weight (dw) with a mean value of 1.1 ng g-1 dw. The levels of PCNs varied largely, with industrial group approximately ten folds higher than those of the rural in riverine sediment. A strong impact by direct discharge from local factories was suggested. Similar compositional profiles were found within groups. High resemblance of compositional profiles between industrial samples and Halowax 1014 was observed. It was indicated that PCNs in riverine sediments were mainly from release of industrial usage, with additional contributions from industrial thermal process at certain sites. In marine sediments, it was suggested that PCNs along the coast of Laizhou Bay were mainly controlled by riverine input. While in the central bay, PCN distributions were possibly impacted by combined multiple factors. - Highlights: → We investigated the PCN levels both in the riverine and marine surface sediments of Laizhou Bay. → PCN concentrations in the river sediments of industrial group were ten times higher than in the rural group. → Leakage from industrial materials and thermal processes were the major sources. → PCNs in the coastal sites were more influenced by the river discharge. → In the centre bay, PCN distributions were possibly impacted by combined multiple factors. - A systematic sampling of riverine and marine sediments was conducted in Laizhou Bay area to investigate the distribution and possible sources of PCNs.
[en] Highlights: • The transition between a fused-ring structure toward its single-ring counterpart is studied. • The change occurs at certain structure instead of a gradual transition. • The fused counterparts can be treated as a modification in the aromatic path of a single ring aromatic motif. • Useful approach to evaluate the formation of defects or larger-rings in graphene motifs. The fused-to-single-ring transition is studied through a 10πe series given the series from naphthalene to annulene. Our results suggest that change occurs at certain structure instead of a gradual transition. In the transition point, given by bicyclo[7.1.0]decapentaene, similar magnetic behavior in comparison to the single ring counterpart is found. The systems can be considered to behave as a whole single aromatic structure where the fused counterparts can be treated as a modification in the aromatic path of a single ring aromatic motif, which can viewed as a useful approach to evaluate the formation of defects or larger-rings in graphene motifs.
[en] A one-pot procedure has been developed for the synthesis of 3-aroyl-2-(polyfluoroalkyl)quinoxalines and 3-aroyl-2-(polyfluoroalkyl)benzo[g]quinoxalines by nitrosation of lithium 3-(polyfluoroalkyl)-1,3-diketonates and subsequent reaction with benzene-1,2-diamine or naphthalene-2,3-diamine, respectively.
[en] We report here the photophysical properties of a naphthalene derivative of a specially designed cryptand system (L). The system exhibits the unusual phenomenon of emission from T2 and T1 states of naphthalene which has been attributed to the inherent rigidity of the system. The results obtained have been analysed by comparison with two other model systems where the flexibility of the fluorophore unit with respect to the receptor moiety have been varied
[en] Ferrocenyl chalcones (Fc-C(O)CH=CH-Ar: Fc-Ar) with mono- and di-1-naphthalenyl moieties (Fc-1Naph and Fc-d1Naph) were prepared and spectroscopically characterized. The enone bridge was in the s-cis conformation and the π-electrons on the C=C bond were further delocalized on the bridge. The naphthalenyl moiety deviates greatly from the enone-Cp plane by 26.9(1) .deg. . Cyclic voltammetry measurements for Fc-1Naph exhibit one reversible cycle for the redox of the ferrocenyl moiety at a lower potential, and one irreversible oxidation peak at the higher potential region. For Fc-d1Naph, the cyclic voltammogram is more featureless. Fluorescence properties for both compounds are active in polar solvents with λem = 500 nm (EtOH) and λem = 512 nm (MeOH) for Fc-1Naph and λem = 496 nm (EtOH) and λem = 508 nm (MeOH) for Fc-d1Naph. The intensity of Fc-d1Naph is more than twice than that of Fc-1Naph. The fluorescence properties for both compounds are inactive in the less polar solvents such as CH3CN, CH2Cl2 and CHCl3
[en] The application of NMR spectroscopy in oriented media to the determination of molecular geometries is illustrated by results for three distinctly different molecules: naphthalene, ethylene oxide and spiropentane. The need for systematic application of vibrational corrections is emphasized and some of the effects associated with the different choices of solvent media are considered
[en] In aquatic systems, one of the non-destructive ways to quantify toxicity of contaminants to plants is to monitor changes in root exudation patterns. In aquatic conditions, monitoring and quantifying such changes are currently challenging because of dilution of root exudates in water phase and lack of suitable instrumentation to measure them. Exposure to pollutants would not only change the plant exudation, but also affect the microbial communities that surround the root zone, thereby changing the metabolic profiles of the rhizosphere. This study aims at developing a device, the RhizoFlowCell, which can quantify metabolic response of plants, as well as changes in the microbial communities, to give an estimate of the stress to which the rhizosphere is exposed. The usefulness of RhizoFlowCell is demonstrated using naphthalene as a test pollutant. Results show that RhizoFlowCell system is useful in quantifying the dynamic metabolic response of aquatic rhizosphere to determine ecosystem health. - A novel RhizoFlowCell system is designed to facilitate non-destructive in situ sampling for biochemical profiling and imaging of the rhizosphere exposed to pollutants in aquatic systems.
[en] The scattering of light at the growing solid-melt interface of biphenyl and naphthalene was studied using the Photon Correlation Spectroscopy technique. The origin of this light scattering remained without a satisfactory explanation since its discovery at the ice-water interface in 1978. Recently, a model based on the segregation of gaseous impurities at the interface and subsequent precipitation of microbubbles was proposed to explain this phenomenon. We report here the first experimental results that confirm the microbbubles hypothesis. (author)