Green electroluminescence generated from the thin film based on a soluble lanthanide complex

Electroluminescent (EL) devices based on a soluble complex Tb(MDP)(3) [Tris-(monododecyl phthalate)Terbium] doped with poly (N-vinylcarbazole) (PVK), (2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) (PBD) were fabricated. The device structures of ITO/PVK/PVK:PBD:Tb(MDp)(2)/Aiq(3)/Al and ITO/PVK:PBD:Tb(MDP)(3)/Alq(3)/Al were employed. The Tb(MDP), as emissive layer was spin-coated. The EL cell exhibited characteristic emission of terbium ion. (C) 2000 Elsevier Science S.A. All rights reserved.

Sol-gel-derived amperometric biosensor for hydrogen peroxide based on methylene green incorporated in Nafion film

A hydrogen peroxide biosensor was fabricated by coating a sol-gel-peroxidase layer onto a Nafion-methylene green modified electrode. Immobilization of methylene green (MG) was attributed to the electrostatic force between MG(+) and the negatively charged sulfonic acid groups in Nafion polymer, whereas immobilization of horseradish peroxidase was attributed to the encapsulation function of the silica sol-gel network. Cyclic voltammetry and chronoamperometry were employed to demonstrate the feasibility of electron transfer between sol-gel-immobilized peroxidase and a glassy carbon electrode. Performance of the sensor was evaluated with respect to response time, sensitivity as well as operational stability. The enzyme electrode has a sensitivity of 13.5 mu A mM(-1) with a detection limit of 1.0 x 10(-7) M H2O2, and the sensor achieved 95% of the steady-state current within 20 s. (C) 2000 Elsevier Science B.V. All rights reserved.

Electroluminescent properties of the Tris-(acetylsalicylate)-terbium (Tb(AS)(3))

The solubility of [Tris-(acetylsalicylate)-terbium] [Tb(AS)(3)] is improved to a greater extent than [Tris-(salicylate)-terbium] [Tb(Sal)(3)] following introduction of a flexible acetyl group. Th3+ binds with acetylsalicylate in solution at low pH value and the resultant Tb(AS)(3) has good solubility in chloroform. A Green EL device with the structure ITO/PVK/PVB:PBD: Tb(AS)(3)/ PBD/Al has been fabricated based on soluble Tb(AS)(3), in which Tb(AS)(3) was first used as an emissive center doped with PVK and PBD. The hole-transporting layer and the emissive layer were formed by spin coating. The device exhibited a highly pure characteristic green light of Tb3+. (C) 2001 Elsevier Science B.V. All rights reserved.

Bright green organic electroluminescent devices based on a novel thermally stable terbium complex

A navel thermally stable terbium carboxylate complex, Tb(MTP)(3)(phen) (MTP=monotetradecyl phthalate, phen=1,10-phehanthroline), was synthesized and characterized. The device structure of glass substrate/indium-tin-oxide/poly(p-phenylenevinylene) (PPV)/poly (N-vinycarbazole) (PVK):Tb(MTP)(3)(phen): 1,3,4-oxadizole derivative (PBD)/tris(8-hydroxyquinoline) (Alq(3))/aluminum (Al) was employed to study the electroluminescent properties of Tb(MTP)(3)(phen). A green emission with extremely sharp spectral band of less than 10 nm at 544 nm peak wavelength was observed. A maximum luminance of 152 cd/m(2) and an external quantum efficiency of 0.017% were achieved at a drive voltage of 24 V. A possible mechanism of energy transfer based on the polymer doped with lanthanide organic complex was also proposed.

Synthesis and high efficiency green light-emitting diode of a soluble polymer

A soluble polymer emitting green color with high efficiency was synthesized. Bright green electroluminescence devices, both single layer and multilayer, were fabricated. The luminous efficiency was improved dramatically. Carrier injection from the electrodes to the emissive layer and concomitant green electroluminescence from the emissive layer were observed. A luminance of 920 cd/m(2) and luminous efficiency of 5.35 1m/W were achieved at a drive voltage of 15 V for the multilayer device. (C) 1997 Elsevier Science S.A.

Synthesis and luminescence characteristics of LiMgAlF6:Ln(3+) (Ln = Ce, Eu, Tb)

By solid state reaction, LiMgAlF6 and LiMgAlF6:Ln(3+) are synthetized with the ratio 120/100/110 of LiF/MgF2/AlF3, at 1008 K, in high-purity Ar stream. Their crystal structure which belongs to hexagonal system are determined by X-Ray-Diffraction (XRD). Luminescence characteristics of Ce3+, Eu3+, Tb3+ and sensitization of Ce3+ to Tb3+ in LiMgAlF6 are studied. It is shown that the sensitization of Ce3+ to Tb3+ is efficient and a bright green emission is observed.

Interaction of brilliant cresyl blue and methylene green with DNA studied by spectrophotometric and voltammetric methods

The binding behavior of two cationic dyes, brilliant cresyl blue (BCB) and methylene green (MG) to calf thymus DNA was studied by spectrophotometric and voltammetric methods. A red shift of the adsorption spectra and hypochromism accompany the binding of BCB and MG to calf thymus DNA. In 5 x 10(-2) mol dm(-3) NaCl, 5 x 10(-3) mol dm(-3) tris-HCl pH 6.87 buffer solution, the apparent binding constants are: K-BCB+ 3.0 x 10(4)M(-1) (N = 4.13) and K-MG+ = 8.8 x 10(4)M(-1) (n = 4.44). Electrochemical studies show that the formal potentials shift negatively upon addition of DNA, indicating that the oxidized forms of the dyes have stronger affinity to DNA than the reduced ones. K-BCB+/K-BCBH and K-MG+/K-MGH are evaluated to be 10.39 and 7.04. respectively. Our investigation suggests that the two cationic dyes interact with DNA predominantly via electrostatic interaction.

Structural analysis of peptides of PSII light-harvesting complexes in siphonous green algae, Codium fragile

peptide composition and arrangement of 4 major light-harvesting complexes LHCP1-3 and LHCP3, isolated from siphonous green algae (Codium fragile (Sur.) Hariot.) were investigated. LHCP1 showed five main peptides, 34.4, 31.5, 29.5, 28.2 and 26.5 kD in SDS-PAGE, the 34.4 and 31.5 kD peptides were never found in higher plants. LHCP3 contained the other four kinds of LHCP1 peptides except 34.4 kD, while LHCP3, consisted of only 28.2 and 26.5 kD peptides. We found that 34.4, 28.2 and 26.5 kD peptides were easy to decompose from LHCP1 when subjected to SDS-PACE without pretreatment. They might be located at the exterior of LHCP1, while the 31.5 and 29.5 kD peptides were at the central part. The 28.2 and 26.5 kD peptides often occurred in CPa, the center complex of PS II. They are possibly the LHC II peptides tightly associated with CC II. According to the results described above, a peptide map of LHCP1 was sketched.

Isolation of PSI from a siphonous marine green alga, Codium fragile

Three different forms of PS I complexes were isolated from a siphonous marine green alga, Codium fragile, by Triton X-100 sucrose gradient centrifugation. Zone III had a Chl a/b>20, and designated as PS I. core complex CC I because it created only CP I band in mild PAGE. Zone IV and V had absorption at 436 and 674 nm, 467 and 650 nm, and 540 nm, suggesting the presence of Chl a, Chl b, siphonaxanthin and siphonein, Chl a/b were 3.23 and 2.4, respectively. Both CP I and CP I a bands were observed when they were subjected to mild PAGE. Therefore, Zone IV and V were different forms of PS I complexes that consisted of CC I and different amount of light-harvesting complex LHC I. Zone III contained only 66 and 56 ku peptides in SDS-PAGE, while Zone IV and V had 4 different LHC I peptides of 25, 26, 26.2 and 27.5 ku in addition to 66, 56 ku peptides. Fluorescence emission spectra showed that efficient energy transfer were kept among pigments in isolated PS I complexes. Excitation energy absorbed by Chl b, siphonaxanthin and siphonein can be transferred to Chl a.

INVESTIGATION OF C-PHYCOCYANIN FROM BLUE-GREEN-ALGA SPIRULINA-PLATENSIS WITH SCANNING TUNNELING MICROSCOPE

C-phycocyanin (C-PC) was isolated from blue-green alga spirulina platensis. A scanning tunneling microscope (STM) has been used to investigate its three-dimensional structure. The samples were dialyzed before the STM experiment, and then deposited on highly oriented pyrolytic graphite (HOPG). The measurement was carried out in ambient condition at room temperature. STM images showed that C-phycocyanin was uniformly distributed on solid-state substrate HOPG. The shape of C-phycocyanin is disklike with a channel in the center. It is concluded that STM has great potential to observe the structure of biliproteins and phycobilisomes.

Comparative analysis of astaxanthin and its esters in the mutant E1 of Haematococcus pluvialis and other green algae by HPLC with a C30 column

A gradient reversed-phase high-performance liquid chromatography (HPLC) method using a C30 column was developed for the simultaneous determination of astaxanthin, astaxanthin monoesters and astaxanthin diesters in the green algae Chlorococcum sp., Chlorella zofingiensis, Haematococcus pluvialis and the mutant E1, which was obtained from the mutagenesis of H. pluvialis by exposure to UV-irradiation and ethyl methanesulphonate (EMS) with subsequent screening using nicotine. The results showed that the contents of total astaxanthins including free astaxanthin and astaxanthin esters ranged from 1.4 to 30.9 mg/g dry biomass in these green algae. The lower total astaxanthin levels (< 2 mg/g dry biomass) were detected in the green algae Chlorococcum sp. and C. zofingiensis. The higher total astaxanthin levels (> 16 mg/g dry biomass) were found in the green alga H. pluvialis and its mutant E1. It is notable that the mutant E1 is found to have considerably higher amounts of total astaxanthin (30.9 mg/g) as compared to the wild strain of H. pluvialis (16.1 mg/g). This indicates that UV-irradiation and EMS compound mutagenesis with subsequent screening using nicotine is an effective method for breeding of a high-producing astaxanthin strain of H. pluvialis. In addition, the green alga C. zofingiensis had a remarkably higher percentage of astaxanthin diesters (76.3% of total astaxanthins) and a remarkably lower percentage of astaxanthin monoesters (18.0% of total astaxanthins) in comparison with H. pluvialis (35.5% for diesters and 60.9% for monoesters), the mutant E1 (49.1% and 48.1%) and Chlorococcum sp. (18.0% and 58.6%).

The possibility analysis of habitats, origin and reappearance of bloom green alga (Enteromorpha prolifera) on inshore of western Yellow Sea

Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008, authors analyze the necessary conditions and possible water area in China producing a large biomass, some reasons for firestorm, and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera. The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons. It was transferred northward by the combination of the flow of rainwater, wind and alongshore marine current. The original region of large biomass produced is possibly located in the southwestern Yellow sea. It will possibly be appearing again in the coming years or in the future. A summary is also given referring to its reproduction, development and distribution worldwide.

Proteasome and NF-kappa B inhibiting phaeophytins from the green alga Cladophora fascicularis

Chemical examination of the green alga Cladophora fascicularis resulted in the isolation and characterization of a new porphyrin derivative, porphyrinolactone (1), along with five known phaeophytins 2-6 and fourteen sterols and cycloartanes. The structure of 1 was determined on the basis of spectroscopic analyses and by comparison of its NMR data with those of known phaeophytins. Compounds 1-6 displayed moderate inhibition of tumor necrosis factor alpha (TNF-alpha) induced nuclear factor-kappa B (NF-kappa B) activation, while 2 and 4 displayed potential inhibitory activity toward proteasome chymotripsin-like activation. The primary structure-activity relationship was also discussed.

Biosorption of Cr(VI) from aqueous solutions by nonliving green algae Cladophora albida

Biosorption of Cr(VI) from aqueous solutions by nonliving green algae Cladophora albida was investigated in batch experiments. The influence of pH, algal dosage, initial Cr(VI) concentration, temperature and coexisting anions on removal efficiencies of C. albida was studied. Cr(VI) removal process was influenced significantly by the variation of pH, and the optimum pH was chosen at a range of 1.0-3.0. The optimum algal dosage 2 g/L was used in the experiment. The removal rate of Cr(VI) was relatively rapid in the first 60 min, but then the rate decreased gradually. Removal mechanism was studied by analyzing Cr(VI) and total Cr in the solution. Biosorption and bioreduction were involved in the Cr(VI) removal. Biosorption of Cr(VI) was the first step. followed by Cr(VI) bioreduction and Cr(III) biosorption on the algal biomass. Actual industrial wastewater was used to evaluate the practicality of the biomass C. albida. From a practical viewpoint, the abundant and economic biomass C. albida could be used for removal of Cr(VI) from wastewater by the reduction of toxic Cr(VI) to less toxic Cr(III). (C) 2008 Elsevier Ltd. All rights reserved.

Crystallographic and NMR studies on sterols from green alga Chaetomorpha basiretorsa Setchell

Chemical investigation of the ethanol extract of the marine green alga Chaetomorpha basiretorsa Setchell led to the isolation of a new sterol stigmast-4,28-dien-3 alpha 6 beta-diol 1 in addition to the five known sterols of beta-lawsaritol 2, saringosterol 3, 24-hydroperoxy-24-vinyl - cholesterol 4, beta-stigmasterol 5, 29-hydroxystigmasta-5, 24(28) -dien-3 beta-ol 6. Compounds were isolated by normal phase silica gel and Sephadex LH - 20 gel colum chromatography, reverse phase HPLC and recrystalization. Their structures were elucidated by spectroscopic methods including MS, IR 1D/2D NMR and X-ray analysis. Cytotoxicity of compounds was screened by using the standard WIT method. All these compounds were isolated from the green alga Chaetomorpha basiretorsa Setchell for the first time and they were inactive (50% inhibitory concentration was greater than 10 mu g /cm(3)) against KB, Bel -7402, PC - 3M, Ketr 3 and MCF - 7 cell lines.