Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NAPHTHALENES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed2004

Vibrational energy relaxation of naphthalene in the S(1) state in various gases.

Time-resolved fluorescence spectra of naphthalene in the S(1) state have been measured in various gases below 10(2) kPa. The band shape of the fluorescence changed in an earlier time region after the photoexcitation when an excess energy (3300 cm(-1)) above the 0-0 transition energy was given. The excitation energy dependence of the fluorescence band shape of an isolated naphthalene molecule was measured separately, and the time dependence of the fluorescence band shape in gases was found to be due to the vibrational energy relaxation in the S(1) state. We have succeeded in determining the transient excess vibrational energy by comparing the time-resolved fluorescence band shape with the excitation energy dependence of the fluorescence band shape. The excess vibrational energy decayed almost exponentially. From the slope of the decay rate against the buffer gas pressure, we have determined the collisional decay rate of the excess vibrational energy in various gases. The dependence of the vibrational energy relaxation rate on the buffer gas species was similar to the case of azulene. The comparisons with the results in the low temperature argon and the energy relaxation rate in the S(0) state in nitrogen were also discussed.

Journal Article↗
PubMed2005

Doppler-free two-photon excitation spectroscopy and the Zeeman effects of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) band of naphthalene-d8.

Doppler-free two-photon excitation spectrum and the Zeeman effect of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) transition of naphthalene-d8 have been measured. 908 lines of Q(Ka)Q(J)KaKc transition of J=0-41, Ka=0-20 were assigned, and the molecular constants of the S1 1B1u(v21=1) state were determined. Perturbations were observed, and those were identified as originating from Coriolis interaction. No perturbation originating from an interaction with triplet state was observed. The Zeeman splittings from lines of a given J were observed to increase with Kc, and those of the Kc=J levels increased linearly with J. The Zeeman effects are shown to be originating from the magnetic moment of the S1 1B1u state, which is along the c axis and is induced by mixing of the S2 1B3u state to the S1 1B1u state by J-L coupling. Rotationally resolved levels were found not to be mixed with a triplet state from the Zeeman spectra. Accordingly, it is concluded that nonradiative decay of an isolated naphthalene excited to low rovibronic levels in the S1 1B1u state does not occur through the intersystem mixing. This is at variance with generally accepted understanding of the pathways of the nonradiative decay.

Journal Article↗
PubMed2005

A density-functional study on pi-aromatic interaction: benzene dimer and naphthalene dimer.

The long-range correction (LC) scheme of density-functional theory (DFT) was applied to the calculation of the pi-aromatic interaction of the benzene dimer and naphthalene dimer. In previous calculations, it was confirmed that the LC scheme [Iikura et al., J. Chem. Phys. 115, 3540 (2001)] gives very accurate potential- energy surfaces (PESs) of small van der Waals (vdW) complexes by combining with the Anderson-Langreth-Lundqvist (ALL) vdW correlation functional [Andersson et al., Phys. Rev. Lett. 76, 102 (1996)] (LC-DFT + ALL). In this study, LC-DFT+ALL method was examined by calculating a wide range of PES of the benzene dimer including parallel, T-shaped, and parallel-displaced configurations. As a result, we succeeded in reproducing very accurate PES within the energy deviance of less than 1 kcalmol in comparison with the results of high-level ab initio molecular-orbital methods at all reference points on the PES. It was also found that LC-DFT + ALL gave accurate results independent of exchange-correlation functional used, in contrast with the strong functional dependencies of conventional pure functionals. This indicates that both exchange repulsion and van der Waals attractive interactions should be correctly incorporated in conventional pure functionals in order to calculate accurate pi-aromatic interactions. We also found that LC-DFT + ALL method has a low basis-set dependency in the calculations of pi-aromatic interactions. The present scheme was also successfully applied to the pi,[ellipsis (horizontal)],pi stacking interactions of naphthalene dimer. This may suggest that LC-DFT + ALL method would be a powerful tool in the calculations of large molecules such as biomolecules.

Journal Article↗
PubMed1999

Excitonic couplings and electronic coherence in bridged naphthalene dimers.

The electronic excitations of naphthalene and a family of bridged naphthalene dimers are calculated and analyzed by using the Collective Electronic Oscillator method combined with the oblique Lanczos algorithm. All experimentally observed trends in absorption profiles and radiative lifetimes are reproduced. Each electronic excitation is linked to the corresponding real-space transition density matrix, which represents the motions of electrons and holes created in the molecule by photon absorption. Two-dimensional plots of these matrices help visualize the degree of exciton localization and explain the dependence of the electronic interaction between chromophores on their separation.

Journal Article↗
PubMed1980

Effect of lysolecithin on the binding of 1-anilino-8-naphthalene sulfonate to apoHDL, apoA-I or apoA-II from human serum high density lipoprotein.

The binding of 1-anilino-8-naphthalene sulfonate to human serum high density apolipoprotein and to apoA-I and apoA-II which are major protein components of high density apolipoprotein was measured by a fluorometric method. The maximum number of 1-anilino-8-naphthalene sulfonate bound to high density apolipoprotein was about 950 mumol per g of protein, and those to apoA-I and apoA-II were 27 and 13 mol per mol of protein (there values correspond to 964 for apoA-I and 765 for apoA-II in mumol per g of protein), respectively. After preincubation of apolipoprotein with lysolecithin (less than 10 microM), the binding affinities for the dye increased twice or more with all the proteins, but the maximum binding numbers changed little. With apoA-I, two mol of the dye were bound with high affinity and lysolecithin did not compete with the dye for the binding sites. The fluorescence intensity of tryptophanyl residues of apoA-I was changed by incubation with lysolecithin at concentrations lower than the critical micellar concentration. These results indicate that the binding of lysolecithin molecules to apoA-I or other proteins makes the protein conformation more suitable for the binding of hydrophobic ligands.

Anilino Naphthalenesulfonates↗
PubMed2004

Two triclinic polymorphs of 2,3,5,6-tetrakis(naphthalen-2-ylsulfanylmethyl)pyrazine.

The title compound, C(48)H(36)N(2)S(4), can be crystallized as two polymorphic structures, (I) and (II), both of which are in the triclinic space group P-1 and possess C(i) symmetry. In the crystal structure of polymorph (I), the adjacent naphthalene moieties are orientated towards one another and are inclined to one another by 78.7 (1) degrees, resulting in weak C-H.pi interactions. In polymorph (II), the adjacent substituents are orientated away from one another, enclosing the pyrazine N atoms. In this way, the S atom of one substituent sits below the plane of the naphthalene ring of the other substituent.

Journal Article↗
PubMed1989

Seasonal Biotransformation of Naphthalene, Phenanthrene, and Benzo[a]pyrene in Surficial Estuarine Sediments.

Transformation rates of naphthalene, phenanthrene, and benzo[a]pyrene in oxidized surficial sediments of a polluted urban estuary, Boston Harbor, Mass., were determined over a period of 15 months. Three sites characterized by muddy sediments were selected to represent a >300-fold range of ambient polycyclic aromatic hydrocarbon (PAH) concentration. Transformation rates were determined by a trace-level radiolabel PAH assay which accounted for PAH mineralization, the formation of polar metabolites, residue, and recovered parental PAHs in sediment slurries. Transformation rates of the model PAHs increased with increasing ambient PAH concentrations. However, turnover times for a given PAH were similar at all sites. The turnover times were as follows: naphthalene, 13.2 to 20.1 days; phenanthrene, 7.9 to 19.8 days, and benzo[a]pyrene, 53.7 to 82.3 days. At specific sites, rates were significantly affected by salinity, occasionally affected by temperature, but not affected by pH over the course of the study. Seasonal patterns of mineralization were observed for each of the PAHs at all sites. The timing of seasonal maxima of PAH mineralization varied from site to site. Seasonal potential heterotrophic activities as measured by acetate and glutamate mineralization rates did not always coincide with PAH mineralization maxima and minima, suggesting that the two processes are uncoupled in estuarine sediments.

Journal Article↗
PubMed1998

Metal toxicity reduction in naphthalene biodegradation by use of metal-chelating adsorbents

A model system comprising microbial degradation of naphthalene in the presence of cadmium has been developed to evaluate metal toxicity associated with polyaromatic hydrocarbon biodegradation and its reduction by the use of unmodified and surfactant-modified clays in comparison with a commercially available chelating resin (Chelex 100; Bio-Rad). The toxicity of cadmium associated with naphthalene biodegradation was shown to be reduced significantly by using the modified-clay complex and Chelex resin, while unmodified clay has no significant impact on this reduction. The degree of metal toxicity reduction can be quantitatively related to the metal adsorption characteristics of these adsorbents, such as adsorption capacity and selectivity.

Journal Article↗
PubMed1990

Purification and properties of ferredoxinNAP, a component of naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816.

One of the three components of the naphthalene dioxygenase occurring in induced cells of Pseudomonas sp. strain NCIB 9816 has been purified to homogeneity. The protein contained 2 g-atoms each of iron and acid-labile sulfur and had an apparent molecular weight of 13,600. The evidence indicates that it is a ferredoxin-type protein that functions as an intermediate electron transfer protein in naphthalene dioxygenase activity.

Dioxygenases↗
PubMed1996

2,4-Dinitrotoluene dioxygenase from Burkholderia sp. strain DNT: similarity to naphthalene dioxygenase.

2,4-Dinitrotoluene (DNT) dioxygenase from Burkholderia sp. strain DNT catalyzes the initial oxidation of DNT to form 4-methyl-5-nitrocatechol (MNC) and nitrite. The displacement of the aromatic nitro group by dioxygenases has only recently been described, and nothing is known about the evolutionary origin of the enzyme systems that catalyze these reactions. We have shown previously that the gene encoding DNT dioxygenase is localized on a degradative plasmid within a 6.8-kb NsiI DNA fragment (W.-C. Suen and J. C. Spain, J. Bacteriol. 175:1831-1837, 1993). We describe here the sequence analysis and the substrate range of the enzyme system encoded by this fragment. Five open reading frames were identified, four of which have a high degree of similarity (59 to 78% identity) to the components of naphthalene dioxygenase (NDO) from Pseudomonas strains. The conserved amino acid residues within NDO that are involved in cofactor binding were also identified in the gene encoding DNT dioxygenase. An Escherichia coli clone that expressed DNT dioxygenase converted DNT to MNC and also converted naphthalene to (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. In contrast, the E. coli clone that expressed NDO did not oxidize DNT. Furthermore, the enzyme systems exhibit similar broad substrate specificities and can oxidize such compounds as indole, indan, indene, phenetole, and acenaphthene. These results suggest that DNT dioxygenase and the NDO enzyme system share a common ancestor.

Amino Acid Sequence↗
PubMed1986

Induction of myeloid differentiation of HL-60 cells with naphthalene sulfonamide calmodulin antagonists.

The naphthalene sulfonamide calmodulin antagonists, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide, both induce limited myeloid differentiation of the human promyelocytic cell line, HL-60. In addition, these inhibitors augment the differentiation observed when HL-60 cells are induced with retinoic acid, dimethyl sulfoxide, or dibutyryl cyclic adenosine monophosphate. The dose-response curve for HL-60 differentiation was consistent with the published 50% inhibitory dose for inhibition of calmodulin-activated phosphodiesterase and with the calmodulin drug-binding potential of N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide and their less active congeners, N-(6-aminohexyl)-1-naphthalenesulfonamide and N-(4-aminobutyl)-2-naphthalenesulfonamide. These effects, of the naphthalene sulfonamide calmodulin antagonists, are consistent with a regulatory role for calmodulin in cell differentiation, but parallel effects on protein kinase C cannot be excluded.

Bucladesine↗
PubMedDate not supplied

[2-Naphthalene-sulphonic acid degrading microorganisms].

Derivatives of anionic surfactants, specially naphthalene sulphonates, when discharged into natural waters are accumulated in waters and sediments because of their poor biodegradability. A four-membered bacterial community, able to degrade the sodium salt of 2-naphthalene-sulphonic acid (2NS), was isolated from Río Reconquista. All the isolated strains consisted of gram-negative, strictly aerobic rods, with a strong proteolytic activity and resistance to high levels of cations like Cr (III), Hg (II), Cd (II) and Pb (II). Some of them were resistant to gentamicin, amikacin and chloramphenicol. These strains appeared to be related to the genera Pseudomonas and Alcaligenes. When isolated, if growing on 2NS, a brown-dark pigment is formed by three of them, resulting in an inhibition of growth. The presence of a Pseudomonas aeruginosa strain avoided the production of pigment and resulting in a complete consume of 2NS.

Alcaligenes↗
PubMed1996

Bacterial Degradation of Low Concentrations of Phenanthrene and Inhibition by Naphthalene

Phenanthrene-degrading bacteria were isolated from enrichment cultures of soils contaminated with creosote and jet fuel. The isolates from the creosote enrichments were classified by fatty acid methyl ester profiles as Acidovorax delafieldii and Sphingomonas paucimobilis; the bacterium from the jet fuel-contaminated soil was not identified and was designated strain JFD11. All three isolates used phenanthrene as a sole carbon and energy source, and two of the isolates used fluoranthene as a sole carbon and energy source. Anthracene and fluorene were cometabolized by all three strains, but pyrene was not transformed. Naphthalene inhibited all of the strains, and 28-h cultures of A. delafieldii were inhibited by naphthalene concentrations as low as 5 ppm. Short-term degradation experiments were undertaken with center-well flasks and concentrations of phenanthrene ranging from 1.2 to 12.0 &mgr;M. Since initial degradation rates were not a function of phenanthrene concentration, it was inferred that the half-saturation constants were less than the lowest phenanthrene concentration tested.

Journal Article↗
PubMed1999

Aldose reductase catalyzes the oxidation of naphthalene-1, 2-dihydrodiol for the formation of ortho-naphthoquinone.

The oxidation of naphthalene-1,2-dihydrodiol (ND) to o-naphthoquinone (NQ) in the lens is believed to be responsible for the formation of cataracts in naphthalene-fed rats. Studies using either recombinant rat lens (RLAR) or human muscle aldose reductase (HMAR) incubated in vitro with ND in the presence of NAD(P) verified that aldose reductase (EC 1.1.1.21) is the dihydrodiol dehydrogenase that catalyzes the oxidation of ND to NQ. Kinetic studies of Vmax/Km indicated that RLAR catalyzes the NAD-dependent oxidation of ND with an optimal pH of 9.0. The corresponding activity of HMAR was lower than that of rat enzyme. The metabolite produced by the incubation of RLAR with ND in the presence of 2-mercaptoethanol and NAD in 20 mM phosphate buffer, pH 7.5, was isolated by C18 reversed-phase high-performance liquid chromatography. The elution profile showed the formation of a new peak that was identical with a peak generated when NQ was incubated under the same condition. The metabolite in both peaks was identified as 4-(2-hydroxyethylsulfanyl)-1, 2-dihydro-1,2-naphthalenedione (HNQ) by 1H and 13C NMR analyses using homonuclear correlation spectroscopy, heteronuclear multiple quantum coherence, and heteronuclear shift correlations via multiple bond connectivities as well as infrared analysis. HNQ is readily autoxidized to 2,3-dihydro-1-oxa-4-thia-9,10-phenanthrenedione. The stoichiometry of 1:1 between the consumption of ND and the formation of NADH for the formation of HNQ implies that rat lens aldose reductase catalyzes a 2e- oxidation of ND to yield the corresponding ketol, which is autoxidized to NQ.

Aldehyde Reductase↗
PubMed1997

Assessment of polychlorinated naphthalenes in aquifer samples for drinking water purposes.

Polychlorinated naphthalenes (PCNs) were identified and quantified in water samples collected from the aquifer of the Llobregat river near Barcelona (NE Spain) in order to establish the source and extent of spreading of the contamination. Many of the identified PCNs were well resolved as single peaks on the chromatograms recorded using high resolution gas chromatography combined with electron ionization high resolution mass spectrometry and single-ion monitoring. The profile and pattern of PCNs found in groundwater samples are similar to those of Halowax 1099. The levels of the sum of mono- to octachloronaphthalenes in the water samples ranged from 0.003 microgram/L to 72.9 micrograms/L.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Separation of naphthalene-2,3-dicarboxaldehyde-derivatized-substance P and its metabolites by micellar electrokinetic chromatography.

This paper describes the development of analytical methodology for the separation of naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized substance P (CBI-SP) and five lysine-containing metabolites by micellar electrokinetic chromatography (MEKC). The effect of surfactant composition and organic modifiers on the separation was investigated. The final separation buffer consisted of 80 mM sodium cholate in 50 mM N-tris (hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), pH 7. All six lysine-containing peptides were separated under these conditions.

Amino Acid Sequence↗
PubMed2001

Determination of free intracellular amino acids in single mouse peritoneal macrophages after naphthalene-2,3-dicarboxaldehyde derivatization by capillary zone electrophoresis with electrochemical detection.

A method is described for the direct identification and quantification of amino acids in individual mouse peritoneal macrophages by capillary zone electrophoresis with electrochemical detection after on-column derivatization with naphthalene-2,3-dicarboxaldehyde (NDA) and CN-. In this method, individual macrophages and then the lysing/ derivatizing buffer are injected into the front end of the separation capillary by electromigration with the aid of an inverted microscope. The front end of the separation capillary is used as a chamber to lyse the macrophage and derivatize its contents, which minimizes dilution of amino acids of a single macrophage during derivatization. Six amino acids (serine, alanine, taurine, glycine, glutamic acid, and aspartic acid) in single mouse peritoneal macrophages have been identified. Quantitation has been accomplished through the use of calibration curves, where the concentration ratios of these standard amino acids are similar to the concentration ratios of amino acids in macrophages. Cellular levels of the amino acids in these cells range from 0.27 +/- 0.20 fmol/ cell for alanine to 6.4 +/- 4.6 fmol/cell for taurine.

Alanine↗
PubMed2001

Respiratory diseases caused by occupational exposure to 1,5-naphthalene-diisocyanate (NDI): Results of workplace-related challenge tests and antibody analyses.

BACKGROUND: 1,5-naphthalene-diisocyanate (NDI) is an aromatic diisocyanate with a very low vapor pressure which is mainly used in the automotive industry. METHODS: In the present study we described five cases with workplace-related asthma and one case with extrinsic allergic alveolitis associated with pulmonary hemorrhage after NDI exposure. RESULTS: Corresponding to case histories, extrinsic alveolitis on asthmatic reactions in three subjects and a rhinitis reaction in one patient could be reproduced by inhalative challenge tests to NDI at a concentration of 10 ppb. Preliminary IgE and IgG antibody analyses in patients' sera did not produce significantly positive results. CONCLUSIONS: According to the outcome of our tests and in comparison with several other studies, we conclude that NDI should be classified as potent airway-sensitizing substance. Improved workplace conditions and decrease in threshold limit values should therefore be recommended.

Adult↗