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1

Synergistic mixtures of fungitoxic monochloro and dichloro-8-quinolinols against five fungi.  

PubMed

Fourteen mono- and dichloro-8-quinolinols were tested against five fungi (Aspergillus niger, A. oryzae, Myrothecium verrucaria, Trichoderma viride, and Mucor circinelloides) and compared with the fungitoxicity of 8-quinolinol in Yeast Nitrogen Base containing 1% D-glucose and 0.088% L-asparagine. All of the compounds were more fungitoxic than 8-quinolinol except for the surprising activity of 8-quinolinol against A. oryzae. Mixtures of the MICs of monochloro- and dichloro-8-quinolinols in which the halogens were in different positions of the quinoline ring showed synergism. Comparable mixtures in which one position of each compound was occupied by the same halogen showed additive activity. In a different study we showed that 3,5,6-, 3,5,7-, 4,5,7-, and 5,6,7-trichloro-8-quinolinols were not toxic to M. circinelloides, whereas the combinations of the correspondingly substituted mono- and dichloro-8-quinolinols as well as 3,6-dichloro- and 5,7-dichloro-8-quinolinols were inhibitory. This indicated that a steric factor can be involved in affecting fungitoxicity. PMID:15487331

Gershon, Herman; Gershon, Muriel; Clarke, Donald D

2004-07-01

2

THE THERMAL DECOMPOSITION OF THE 5,7-DIHALO-8QUINOLINOL RARE EARTH METAL CHELATES  

Microsoft Academic Search

S>The thermal decomposition of the 5,7-dichloro-, 5,7dibromo- and 5,7-; diiodo-8-quinolinol chelates of La, Ce, Pr, Nd, Sm, and Y was investigated on the ; thermobalance. The chelates decomposed in the temperature range from 65 to 125 ; deg C while the oxide levels were obtained from 395 to 805 deg C. Although the ; chelate thermal stability temperatures varied little

W Wendlandt

1957-01-01

3

NMR study of O and N, O-substituted 8-quinolinol derivatives.  

PubMed

The (1)H and (13)C NMR spectral study of several biologically active derivatives of 8-quinolinol have been made through extensive NMR studies including homodecoupling and 2D-NMR experiments such as COSY-45, NOESY, and HeteroCOSY. Electron donating resonance and electron withdrawing inductive effect of several groups showed marked changes in chemical shifts of nuclei at the seventh positions of O-substituted quinolinols (2-15). Although in N-alkyl, 8-alkoxyquinolinium halides (16-21), ring A rightly showed low frequency chemical shift values. PMID:24327567

Mastoor, Sobia; Faizi, Shaheen; Saleem, Rubeena; Siddiqui, Bina Shaheen

2014-03-01

4

Substitutional complexometric determination of magnesium in homogeneous water-dioxan medium, based on decomposition of MgEDTA with 8-quinolinol and titration of released EDTA with calcium.  

PubMed

A method based on a substitution reaction between MgEDTA and 8-quinolinol, and titration of the liberated EDTA with calcium is proposed. The reaction is performed in homogeneous 50%-60% dioxan medium at ph 10, in which magnesium forms a soluble and stable 8-quinolinol complex. PMID:18965572

Karolev, A

1992-12-01

5

Antifungal activity of substituted 8-quinolinol-5- and 7-sulfonic acids: a mechanism of action is suggested based on intramolecular synergism  

Microsoft Academic Search

8-Quinolinol-5-sulfonic acid was nearly devoid of antimicrobial activity, due to what was believed to be an unfavorable partition coefficient. Since twenty six 8-quinolinol-5- and 7-sulfonic acids were available from our previous work, they were tested against six fungi. The 7-chloro and 7-bromo-5-sulfonic acids and the 5-chloro and 5-bromo-7-sulfonic acids showed fungal inhibition within one order of magnitude of that of

Herman Gershon; Muriel Gershon; Donald D. Clarke

2003-01-01

6

Synergistic extraction equilibrium of gallium(III) with di(2-ethylhexyl)phosphoric acid and 8-quinolinol derivatives into supercritical carbon dioxide.  

PubMed

The synergistic effect of five 8-quinolinol derivatives (HQs) on the extraction of gallium(III) with di(2-ethylhexyl)-phosphoric acid (D2EHPA or HA) from weak nitric acid into supercritical carbon dioxide (SC-CO(2)) was investigated. 8-Quinolinol (Hq), 5-ethoxymethyl-8-quinolinol (HO(2)q), 5-hexyloxymethyl-8-quinolinol (HO(6)q), 5-(2,2,2-trifluoroethoxymethyl)-8-quinolinol (HFO(2)q), and 5-chloro-8-quinolinol (5-Cl-Hq) were used as synergists. Synergism was observed for all of the HQs. The synergistic effect increased in the following order: Hq < HO(2)q < HFO(2)q < 5-Cl-Hq ? HO(6)q. The extent of synergism can be related to both the distribution constant and the acid dissociation constant of the HQ. The synergistic extraction equilibrium of gallium(III) with D2EHPA and 5-Cl-Hq into SC-CO(2) was investigated; the results suggest that the composition of the extracted complex is as GaA(2)QHA. The synergistic extraction mechanism was the same for both SC-CO(2) and n-heptane. The synergistic extraction equilibrium constants in both cases were calculated based on the experimental results. PMID:23303097

Ohashi, Akira; Kawashima, Natsumi; Sato, Kazuaki; Kim, Haeng-Boo

2013-01-01

7

Molecular optical switches based on [Ru(OAc)(2cqn)2NO](H2cqn=2-chloro-8-quinolinol)  

NASA Astrophysics Data System (ADS)

Photoisomerization from cis-2 [Ru(OAc)(2cqn)2NO] (H2cqn=2-chloro-8-quinolinol) to cis-1 isomer was studied quantitatively and the effect of wavelength on isomerization was investigated. The main absorption band in UV-Vis region for cis-1 and cis-2 isomer was observed from 350 nm to 500 nm, and the kinetic study showed that the photoisomerization from cis-2 to cis-1 isomer was first-order and the rate constant (k) is 0.00022 (s-1) at 420 nm, 0.00018 (s-1) at 475 nm, 0.00011 (s-1) at 550 nm, respectively. Density functional theory (DFT) calculation suggested that the electronic transition from a ligand based orbital to an antibonding overlap of the Ru(d) and ?* NO(p) orbitals control the photo induced reactivity of [Ru(OAc)(2cqn)2NO] complexes. The study provides basic information to design the molecular optical switches and advance optoelectronic materials based on nitrosylruthenium(II) complexes.

Wang, Hongfei; Jin, Xiaowei; Wang, Jianru; Qiao, Xiaoyan

2012-01-01

8

Potent inhibition of dinuclear zinc(II) peptidase, an aminopeptidase from Aeromonas proteolytica, by 8-quinolinol derivatives: inhibitor design based on Zn2+ fluorophores, kinetic, and X-ray crystallographic study.  

PubMed

The selective inhibition of an aminopeptidase from Aeromonas proteolytica (AAP), a dinuclear Zn(2+) hydrolase, by 8-quinolinol (8-hydroxyquinoline, 8-HQ) derivatives is reported. We previously reported on the preparation of 8-HQ-pendant cyclens as Zn(2+) fluorophores (cyclen is 1,4,7,10-tetraazacyclododecane), in which the nitrogen and phenolate of the 8-HQ units (as well as the four nitrogens of cyclen) bind to Zn(2+) in a bidentate manner to form very stable Zn(2+) complexes at neutral pH (K (d) = 8-50 fM at pH 7.4). On the basis of this finding, it was hypothesized that 8-HQ derivatives have the potential to function as specific inhibitors of Zn(2+) enzymes, especially dinuclear Zn(2+) hydrolases. Assays of 8-HQ derivatives as inhibitors were performed against commercially available dinuclear Zn(2+) enzymes such as AAP and alkaline phosphatase. 8-HQ and the 5-substituted 8-HQ derivatives were found to be competitive inhibitors of AAP with inhibition constants of 0.16-29 ?M at pH 8.0. The nitrogen at the 1-position and the hydroxide at the 8-position of 8-HQ were found to be essential for the inhibition of AAP. Fluorescence titrations of these drugs with AAP and an X-ray crystal structure analysis of an AAP-8-HQ complex (1.3- resolution) confirmed that 8-HQ binds to AAP in the "Pyr-out" mode, in which the hydroxide anion of 8-HQ bridges two Zn(2+) ions (Zn1 and Zn2) in the active site of AAP and the nitrogen atom of 8-HQ coordinates to Zn1 (Protein Data Bank code 3VH9). PMID:22311113

Hanaya, Kengo; Suetsugu, Miho; Saijo, Shinya; Yamato, Ichiro; Aoki, Shin

2012-04-01

9

Studies of the degradation mechanism of organic light-emitting diodes based on tris(8-quinolinolate)aluminum Alq and 2-tert-butyl-9,10-di(2-naphthyl)anthracene TBADN  

NASA Astrophysics Data System (ADS)

Previously, radical cation of tris(8-quinolinolate)aluminum (Alq+) has been associated with the instability of Alq films subjected to holes-only electrical current. Yet, the questions remain (i) whether Alq+ is the primary source of the intrinsic degradation of bipolar organic light-emitting diodes (OLEDs) based on Alq, (ii) whether Alq+ reactions result in deep charge traps in holes-only devices as found in bipolar counterparts, and (iii) whether radical cations can be a common source of degradation of OLEDs irrespective of materials. With regards to generality of hole-current-related degradation, it is interesting to examine the behavior of 9,10-diarylanthracenes (DAAs)the practically important class of blue-fluorescing light-emitting-layer hosts. These questions prompted our comparative study of the effects of unipolar currents in Alq and 2-t-butyl-9,10-di(2-naphthyl)anthracene (TBADN), which was chosen as a representative material of the DAA class. First, we identified device structures allowing for rigorous and stable unipolar conduction. Interestingly, even in pristine holes-only devices, our voltammetric measurements indicated that Alq contains a substantial density of deep hole traps (far deeper than what can be explained by energetic disorder), which can be charged by passing holes-only current and seemingly discharged by exposure to white light. As for aged holes-only Alq devices, they exhibited symptoms qualitatively matching those of aged bipolar Alq devices, viz., photoluminescence (PL) loss, transition voltage (V0) rise, and drive voltage (Vd) rise. Notably, PL and V0 are linearly correlated in both holes-only and bipolar devices, which reinforces the supposed link between Alq+ and the degradation in both types of devices. Yet, there are indications the Alq+ instability may not be the only degradation pathway in bipolar devices. Even though our observations for holes-only Alq devices agree qualitatively with previously reported ones, we observe far slower degradation rates [Alq PL fades up to 500 times slower in holes-only devices, while Alq electroluminescence (EL) fades 50 times slower in bipolar control devices]. It is possible that impurities play a significant, perhaps crucial role in the degradation mechanism of both bipolar and holes-only devices, especially the relatively shorter-lived ones. In sharp contrast to Alq, all three observables (PL, V0, and Vd) indicate that holes-only current in TBADN (neat or doped with a perylene-based blue dopant) does not result in degradation in the time that is sufficient for the corresponding bipolar control devices to lose 60%-80% of EL and 20%-30% of PL. We find that the electrons-only current in Alq or TBADN does not result in degradation either. Thus, the degradation of Alq and DAA bipolar devices may be caused by fundamentally dissimilar mechanisms: while hole current may damage the former, it does not appear to affect the latter, suggesting that the initiation step is different.

Jarikov, Viktor V.; Kondakov, Denis Y.

2009-02-01

10

Antimicrobial Activity of 8-Quinolinols, Salicylic Acids, Hydroxynaphthoic Acids, and Salts of Selected Quinolinols with Selected Hydroxy-Acids  

PubMed Central

Seventy-seven compounds were screened by the disc-plate method against strains of five bacteria and five fungi. A new constant was proposed to describe the antimicrobial activity of a compound in a defined system of organisms. This constant includes not only the inhibitory level of activity of the material but also the number of organisms inhibited. This constant, the antimicrobial spectrum index, was compared with the antimicrobial index of Albert. PMID:13898066

Gershon, Herman; Parmegiani, Raulo

1962-01-01

11

Synthesis, Characterization and Antimicrobial Activity of Metal Chelates of 5-(4-Chloro phenyl(1, 3, 4)thiadiazol-2-ylamino methylene)-8-hydroxy quinoline  

Microsoft Academic Search

Chloromethyl-8-quinolinol was condensed stoichiometrically with 5-(4-chlorophenyl)-(1,3,4) thiadiazol-2-ylamine in the presence of sodium bicarbonate. The resulting 5-(4-chlorophenyl-(1,3,4)thiadiazol-2-ylamino methylene)-8-quinolinol (CTAQ) was characterized by elemental analysis and spectral studies. The transition metal chelates viz . Cu 2+ , Ni 2+ , Co 3+ , Mn 2+ and Zn 2+ of CTAQ were prepared and characterized by metal-ligand (M:L) ratio, IR and reflectance spectroscopies

DIVYESH K. PATEL; ARUN SINGH

2009-01-01

12

Synthesis and optical properties of aluminum and zinc quinolates through styryl subsituent in 2-position  

Microsoft Academic Search

4-Methyl(methoxy or chloro)benzaldehyde reacted with 2-methyl-8-quinolinol to afford the corresponding substituted 2-styryl-8-quinolinol. The latter was used as chelating ligand to prepare aluminum and zinc complexes. The spectroscopic, thermal, thermomechanical and optical properties of these complexes were investigated. The thermal stability of the complexes was much higher than the reference complexes AlQ3 and ZnQ2. The char yield at 800C in N2

Vasilis P. Barberis; John A. Mikroyannidis

2006-01-01

13

Spectrophotometric determination of metronidazole and secnidazole in pharmaceutical preparations  

Microsoft Academic Search

A rapid and sensitive spectrophotometric method is proposed for determination of metronidazole and secnidazole. The method depends on the reduction of metronidazole and secnidazole molecule with zinc dust and hydrochloric acid flowed by diazotization and coupling with 8-quinolinol to give red colored chromogens easily measured spectrophotometrically which has ?max=500nm. The experimental conditions were optimized and Berr's law was obeyed over

T. Saffaj; M. Charrouf; A. Abourriche; Y. Abboud; A. Bennamara; M. Berrada

2004-01-01

14

Determination of Microamount of Aluminum, Chromium, Copper, Iron, Manganese, Molybdenum and Nickel in Pure Water by Extraction Photometry  

Microsoft Academic Search

Aluminum, iron (III), copper, and molybdenum 8-quinolinol complexes, chromium (III) and manganese 8-hydroxyquinaldine complexes and nickel dimethylglyoxime complex can be quantitatively extracted into chloroform from large volumes of aqueous phases adjusted to an approriate pH for each metal. These metals can be determined by measuring the absorbance of the organic phases containing their complexes at an appropriate wavelength for each

Kenji MOTOJIMA; Nasumi ISHIWATARI

1965-01-01

15

Selective Precipitation of Thorium lodate from a Tartaric Acid-Hydrogen Peroxide Medium Application to Rapid Spectrophotometric Determination of Thorium in Silicate Rocks and in Ores  

USGS Publications Warehouse

This paper presents a selective iodate separation of thorium from nitric acid medium containing d-tartaric acid and hydrogen peroxide. The catalytic decomposition of hydrogen peroxide is prevented by the use of 8quinolinol. A few micrograms of thorium are separated sufficiently clean from 30 mg. of such oxides as cerium, zirconium, titanium, niobium, tantalum, scandium, or iron with one iodate precipitation to allow an accurate determination of thorium with the thoronmesotartaric acid spectrophotometric method. The method is successful for the determination of 0.001% or more of thorium dioxide in silicate rocks and for 0.01% or more in black sand, monazite, thorite, thorianite, eschynite, euxenite, and zircon.

Grimaldi, F.S.

1957-01-01

16

Stabilized liquid membrane device (SLMD) for the passive, integrative sampling of labile metals in water  

USGS Publications Warehouse

A stabilized liquid membrane device (SLMD) is described for potential use as an in situ, passive, integrative sampler for cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in natural waters. The SLMD (patent pending) consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equal mixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagent mixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on sampler configuration, concentration factors of several thousand can be realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow on the sampling rate are currently under investigation.

Brumbaugh, W.G.; Petty, J.D.; Huckins, J.N.; Manahan, S.E.

2002-01-01

17

Photocontrolled nitric oxide release from two nitrosylruthenium isomer complexes and their potential biomedical applications.  

PubMed

Nitric oxide (NO) has key regulatory roles in various biological and medical processes. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO donors. Release of NO from metal-nitrosyl complexes upon exposure to light is a strategy that could allow for the site-specific delivery of the reactive species NO to physiological targets. The photodissociation of NO from two nitrosylruthenium(II) isomer complexes {cis- and trans-[Ru(OAc)(2mqn)(2)NO]} was demonstrated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry spectra, and electron paramagnetic resonance spectra further prove the photoinduced NO release by spin trapping of NO free radicals upon photoirradiation. Real-time NO release was quantitatively measured by electrochemistry with an NO-specific electrode. The quantitative control of NO release from [Ru(OAc)(2mqn)(2)NO] in aqueous solutions was done by photoirradiation at different wavelengths. Both isomers show photoinduced damage on plasmid DNA, but the trans isomer has higher cytotoxicity and photocytotoxicity activity against the HeLa tumor cell line than that of the cis isomer. Nitrosylruthenium(II) complex, with 8-quinolinol derivatives as ligands, has a great potential as a photoactivated NO donor reagent for biomedical applications. PMID:25621873

Liu, Jiao; Duan, Qingqing; Wang, Jianru; Song, Zhen; Qiao, Xiaoyan; Wang, Hongfei

2015-01-01

18

Photoisomerization and structural dynamics of two nitrosylruthenium complexes: a joint study by NMR and nonlinear IR spectroscopies.  

PubMed

In this work, the photoisomerization and structural dynamics of two isomeric nitrosylruthenium(ii) complexes [Ru(OAc)(2cqn)2NO] (H2cqn = 2-chloro-8-quinolinol) in CDCl3 and DMSO are examined using NMR and IR spectroscopic methods. The two N atoms in the 2cqn ligand are in trans position in the synthesized cis-1 isomer, while they are in cis position in the cis-2 isomer. Kinetics monitored by NMR spectroscopy shows that the rate constant of photoisomerization from cis-2 to cis-1 isomer depends on the wavelength of irradiation and solvent polarity; it proceeds faster on irradiating near the absorption peak in the UV-Vis region, and also in more polar solvents (DMSO). Density functional theory computation indicates that the peculiarity of [Ru(ii)-NO(+)] group affects the structure and reactivity of the nitrosylruthenium complexes. Using the nitrosyl stretching (?NO) to be vibrational probe, the structural dynamics and structural distributions of the cis-1 and cis-2 isomers are examined by steady-state linear infrared and ultrafast two-dimensional infrared (2D IR) spectroscopies. The structural and photochemical aspects of the observed spectroscopic parameters are discussed in terms of solute-solvent interactions for the two nitrosylruthenium complexes. PMID:25285659

Wang, Jianru; Yang, Fan; Zhao, Yan; Yu, Pengyun; Qiao, Xiaoyan; Wang, Jianping; Wang, Hongfei

2014-11-21

19

Photocontrolled nitric oxide release from two nitrosylruthenium isomer complexes and their potential biomedical applications  

NASA Astrophysics Data System (ADS)

Nitric oxide (NO) has key regulatory roles in various biological and medical processes. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO donors. Release of NO from metal-nitrosyl complexes upon exposure to light is a strategy that could allow for the site-specific delivery of the reactive species NO to physiological targets. The photodissociation of NO from two nitrosylruthenium(II) isomer complexes {cis- and trans-[Ru(OAc)2NO]} was demonstrated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry spectra, and electron paramagnetic resonance spectra further prove the photoinduced NO release by spin trapping of NO free radicals upon photoirradiation. Real-time NO release was quantitatively measured by electrochemistry with an NO-specific electrode. The quantitative control of NO release from [Ru(OAc)2NO] in aqueous solutions was done by photoirradiation at different wavelengths. Both isomers show photoinduced damage on plasmid DNA, but the trans isomer has higher cytotoxicity and photocytotoxicity activity against the HeLa tumor cell line than that of the cis isomer. Nitrosylruthenium(II) complex, with 8-quinolinol derivatives as ligands, has a great potential as a photoactivated NO donor reagent for biomedical applications.

Liu, Jiao; Duan, Qingqing; Wang, Jianru; Song, Zhen; Qiao, Xiaoyan; Wang, Hongfei

2015-01-01

20

Highly efficient blue organic light-emitting diodes using quantum well-like multiple emissive layer structure.  

PubMed

In this study, the properties of blue organic light-emitting diodes (OLEDs), employing quantum well-like structure (QWS) that includes four different blue emissive materials of 4,4'-bis(2,2'-diphenylyinyl)-1,1'-biphenyl (DPVBi), 9,10-di(naphth-2-yl)anthracene (ADN), 2-(N,N-diphenyl-amino)-6-[4-(N,N-diphenyl amine)styryl]naphthalene (DPASN), and bis(2-methyl-8-quinolinolate)-4-(phenyl phenolato) aluminum (BAlq), were investigated. Conventional QWS blue OLEDs composed of multiple emissive layers and charge blocking layer with lower highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy level, and devices with triple emissive layers for more significant hole-electron recombination and a wider region for exciton generation were designed. The properties of triple emissive layered blue OLEDs with the structure of indium tin oxide (ITO) /N,N'-diphenyl-N,N'-bis(1-naphthyl-phenyl)-(1,1'-biphenyl)-4,4'-diamine (NPB) (700 ?)/X (100 ?)/BAlq (100 ?)/X (100 ?)/4,7-diphenyl-1,10-phenanthroline (Bphen) (300 ?)/lithium quinolate (Liq) (20 ?)/aluminum (Al) (1,200 ?) (X?=?DPVBi, ADN, DPASN) were examined. HOMO-LUMO energy levels of DPVBi, ADN, DPASN, and BAlq are 2.8 to 5.9, 2.6 to 5.6, 2.3 to 5.2, and 2.9 to 5.9eV, respectively. The OLEDs with DPASN/BAlq/DPASN QWS with maximum luminous efficiency of 5.32cd/A was achieved at 3.5V. PMID:24940170

Yoon, Ju-An; Kim, You-Hyun; Kim, Nam Ho; Yoo, Seung Il; Lee, Sang Youn; Zhu, Fu Rong; Kim, Woo Young

2014-01-01

21

Highly efficient blue organic light-emitting diodes using quantum well-like multiple emissive layer structure  

PubMed Central

In this study, the properties of blue organic light-emitting diodes (OLEDs), employing quantum well-like structure (QWS) that includes four different blue emissive materials of 4,4?-bis(2,2?-diphenylyinyl)-1,1?-biphenyl (DPVBi), 9,10-di(naphth-2-yl)anthracene (ADN), 2-(N,N-diphenyl-amino)-6-[4-(N,N-diphenyl amine)styryl]naphthalene (DPASN), and bis(2-methyl-8-quinolinolate)-4-(phenyl phenolato) aluminum (BAlq), were investigated. Conventional QWS blue OLEDs composed of multiple emissive layers and charge blocking layer with lower highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy level, and devices with triple emissive layers for more significant hole-electron recombination and a wider region for exciton generation were designed. The properties of triple emissive layered blue OLEDs with the structure of indium tin oxide (ITO) /N,N?-diphenyl-N,N?-bis(1-naphthyl-phenyl)-(1,1?-biphenyl)-4,4?-diamine (NPB) (700 ?)/X (100 ?)/BAlq (100 ?)/X (100 ?)/4,7-diphenyl-1,10-phenanthroline (Bphen) (300 ?)/lithium quinolate (Liq) (20 ?)/aluminum (Al) (1,200 ?) (X?=?DPVBi, ADN, DPASN) were examined. HOMO-LUMO energy levels of DPVBi, ADN, DPASN, and BAlq are 2.8 to 5.9, 2.6 to 5.6, 2.3 to 5.2, and 2.9 to 5.9eV, respectively. The OLEDs with DPASN/BAlq/DPASN QWS with maximum luminous efficiency of 5.32cd/A was achieved at 3.5V. PMID:24940170

2014-01-01

22

A novel method applied in determination and assessment of trace amount of lead and cadmium in rice from four provinces, China.  

PubMed

Heavy metal contamination of soils or water can lead to excessive lead (Pb) and cadmium (Cd) levels in rice. As cumulative poisons, consumption of Pb and Cd in contaminated rice may cause many toxic effects in humans. In the present study, Pb and Cd levels in rice samples from Hubei, Jiangxi, Heilongjiang, and Guangdong provinces in China were analyzed by cloud point extraction and graphite furnace atomic absorption spectrometry (GFAAS). The heavy metals in the rice samples were reacted with 8-quinolinol to form a complex at pH 9.0 and 40C. Analytes were quantitatively extracted to a surfactant-rich phase (Triton X-45) after centrifugation and analyzed by GFAAS. The effects of experimental conditions, including pH, concentration of reagents, and equilibration time and temperature, on cloud point extraction were optimized efficiently using Plackett-Burman and Box-Behnken experimental designs. Under the optimum conditions, good linearity was observed in the concentration ranges of 0.5-5 g/L for Pb and 0.05-0.50 g/L for Cd. The limits of detection were 0.043 g/L for Pb with a concentration factor of 24.2 in a 10 mL sample and 0.018 g/L for Cd with a concentration factor of 18.4 in a 10 mL sample. Twenty rice samples from four provinces were analyzed successfully, and the mean levels of Pb and Cd in the rice were all below their maximum allowable concentrations in China. Comparing the tolerable daily intakes given by FAO/WHO with the mean estimated daily intakes; Pb and Cd mean daily intake through rice consumption were 0.84 g/kg bw/day and 0.40 g/kg bw/day, which were lower than the tolerable daily intakes. PMID:25251454

Li, Shan; Wang, Mei; Yang, Bingyi; Zhong, Yizhou; Feng, Le

2014-01-01

23

A Novel Method Applied in Determination and Assessment of Trace Amount of Lead and Cadmium in Rice from Four Provinces, China  

PubMed Central

Heavy metal contamination of soils or water can lead to excessive lead (Pb) and cadmium (Cd) levels in rice. As cumulative poisons, consumption of Pb and Cd in contaminated rice may cause many toxic effects in humans. In the present study, Pb and Cd levels in rice samples from Hubei, Jiangxi, Heilongjiang, and Guangdong provinces in China were analyzed by cloud point extraction and graphite furnace atomic absorption spectrometry (GFAAS). The heavy metals in the rice samples were reacted with 8-quinolinol to form a complex at pH 9.0 and 40C. Analytes were quantitatively extracted to a surfactant-rich phase (Triton X-45) after centrifugation and analyzed by GFAAS. The effects of experimental conditions, including pH, concentration of reagents, and equilibration time and temperature, on cloud point extraction were optimized efficiently using PlackettBurman and BoxBehnken experimental designs. Under the optimum conditions, good linearity was observed in the concentration ranges of 0.55 g/L for Pb and 0.050.50 g/L for Cd. The limits of detection were 0.043 g/L for Pb with a concentration factor of 24.2 in a 10 mL sample and 0.018 g/L for Cd with a concentration factor of 18.4 in a 10 mL sample. Twenty rice samples from four provinces were analyzed successfully, and the mean levels of Pb and Cd in the rice were all below their maximum allowable concentrations in China. Comparing the tolerable daily intakes given by FAO/WHO with the mean estimated daily intakes; Pb and Cd mean daily intake through rice consumption were 0.84 g/kg bw/day and 0.40 g/kg bw/day, which were lower than the tolerable daily intakes. PMID:25251454

Li, Shan; Wang, Mei; Yang, Bingyi; Zhong, Yizhou; Feng, Le

2014-01-01

24

Bioactive Pyridine-N-oxide Disulfides from Allium stipitatum  

PubMed Central

From Allium stipitatum, three pyridine-N-oxide alkaloids (1-3) possessing disulfide functional groups were isolated. The structures of these natural products were elucidated by spectroscopic means as 2-(methyldithio)pyridine-N-oxide (1), 2-[(methylthiomethyl)dithio]pyridine-N-oxide (2), and 2,2?-dithio-bis-pyridine-N-oxide (3). The proposed structure of 1 was confirmed by synthetic S-methylthiolation of commercial 2-thiopyridine-N-oxide. Compounds 1 and 2 are new natural products, and 3 is reported for the first time from an Allium species. All compounds were evaluated for activity against fast-growing species of Mycobacterium, methicillin-resistant Staphylococcus aureus, and a multidrug-resistant (MDR) variants of S. aureus. Compounds 1 and 2 exhibited minimum inhibitory concentrations (MICs) of 0.5-8 ?g/mL against these strains. A small series of analogues of 1 were synthesized in an attempt to optimize antibacterial activity, although the natural product had the most potent in vitro activity. In a whole-cell assay at 30 ?g/mL, 1 was shown to give complete inhibition of the incorporation of 14C-labeled acetate into soluble fatty acids, indicating that it is potentially an inhibitor of fatty acid biosynthesis. In a human cancer cell line antiproliferative assay, 1 and 2 displayed IC50 values ranging from 0.3 to 1.8 ?M with a selectivity index of 2.3 when compared to a human somatic cell line. Compound 1 was evaluated in a microarray analysis that indicated a similar mode of action to menadione and 8-quinolinol by interfering with the thioredoxin system and up-regulating the production of various heat shock proteins. This compound was also assessed in a mouse model for in vivo toxicity. PMID:19093848

O'Donnell, Gemma; Poeschl, Rosemarie; Zimhony, Oren; Gunaratnam, Mekala; Moreira, Joao B. C.; Neidle, Stephen; Evangelopoulos, Dimitrios; Bhakta, Sanjib; Malkinson, John P.; Boshoff, Helena I.; Lenaerts, Anne; Gibbons, Simon

2008-01-01

25

S-shaped decanuclear heterometallic [Ni8Ln2] complexes [Ln(III) = Gd, Tb, Dy and Ho]: theoretical modeling of the magnetic properties of the gadolinium analogue.  

PubMed

The reaction of 8-quinolinol-2-carboaldoxime (LH2) with Ni(II) and Ln(III) salts afforded the heterometallic decanuclear compounds [Ni8Dy2(?3-OH)2(L)8(LH)2(H2O)6](ClO4)216H2O (1), [Ni8Gd2(?3-OH)2(L)8(LH)2(H2O)4(MeOH)2](NO3)212H2O (2), [Ni8Ho2(?3-OH)2(L)8(LH)2(H2O)4(MeOH)2](ClO4)22MeOH12H2O (3) and [Ni8Tb2 (?3-OH)2(L)8(LH)2(MeOH)4(OMe)2]2CH2Cl28H2O (4). While compounds 1-3 are dicationic, compound 4 is neutral. These compounds possess an S-shaped architecture and comprise a long chain of metal ions bound to each other. In all the complexes, the eight Ni(II) and two Ln(III) ions of the multimetallic ensemble are hold together by two ?3-OH, eight dianionic (L(2-)) and two monoanionic oxime ligands (LH(-)) whereas compound 4 has two ?3-OH, eight dianionic (L(2-)), two monoanionic oxime ligands (LH(-)) and two terminal methoxy (MeO(-)) ligands. The central portion of the S-shaped molecular wire is made up of an octanuclear Ni(II) ensemble which has at its two ends the Ln(III) caps. Magnetic studies on 1-4 reveal that the magnetic interactions between neighboring metal ions are negligible at room temperature. On the other hand, at lower temperatures in all the compounds anti-ferromagnetic interactions seem to be dominated. Analysis of the magnetic data for the Gd(III) derivative indicates Ni(II)-Ni(II) anti-ferromagnetic interactions and Gd(III)-Ni(II) ferromagnetic interactions at low temperatures. A theoretical density functional study on the magnetic behavior of the Gd(III) derivative suggests that while the weak ferromagnetic interaction between Gd(III) and Ni(II) is in line with the expectation of the magnetic interactions between orthogonal d and f orbitals, antiferromagnetic Ni(II)-Ni(II) interactions are related to the wide Ni-O-Ni angles (?102) and quasi-planar conformation of the Ni2O2 core. PMID:24876072

Hossain, Sakiat; Das, Sourav; Chakraborty, Amit; Lloret, Francesc; Cano, Joan; Pardo, Emilio; Chandrasekhar, Vadapalli

2014-07-14