A new beta-diketone complex with high color purity

In this work a new europium (III) complex with the following formula NH(4) [Eu(bmdm)(4)] was synthesized and characterized. The bmdm (butyl methoxy-dibenzoyl-methane) is a P-diketone molecule used as UV radiation absorber in sunscreen formulations. Coordination of this ligand to the Eu(3+) ion was confinned by FT-IR, while the Raman spectrum suggests the presence of NH(4)(+) ions. The photoluminescence spectra present narrow lines arising from f-f intra-configurational transitions (5)D(0-)(7)F(0,1,2,3,4), dominated by the hypersensitive (5)D(0)-(7)F(2) transition. In the spectrum recorded at 77 K, all transitions split into 2J + 1 lines suggesting that there is just one symmetry site around Eu(3+) ion. This symmetry is not centrosymmetric. The calculated intensity parameters are ohm(2) = 30.5 x 10(-20) cm(2) and ohm(4) = 5.91 x 10(-20) cm(2) for this complex. The CIE chromaticity coordinates (x = 0.67 and y = 0.32) show a dominant wavelength of 615 nm. The color gamut achieved by this complex is a 100% in the CIE color space. (c) 2005 Elsevier B.V. All rights reserved.

Broadband Dual-Polarized Antenna with High Port Isolation and Polarization Purity

This paper presents a novel high symmetry balun which significantly improves the performance of dipole-based dual-polarized antennas. The new balun structure provides enhanced differential capability leading to high performance in terms of port-to-port isolation and far-field cross polarization. An example antenna using this balun is proposed. The simulated results show 53.5% of fractional bandwidth within the band 1.71−2.96 GHz (VSWR<1.5) and port-to-port isolation >59 dB. The radiation characteristic shows around 9 dBi of gain and far-field cross polarization <−48 dBi over the entire bandwidth. The detailed balun functioning and full antenna measurements will be presented during the conference. Performance comparison with similar structures will be also provided.

Purity evaluation and influence of carbon nanotube on carbon nanotube/graphite thermal stability

High resolution thermogravimetry has been used to evaluate the carbonaceous content in a commercial sample of single-walled carbon nanotube (SWNT). The content of SWNTs in the sample was found to be at least 77mass% which was supported by images obtained with scanning and transmission electron microscopies (SEM and TEM). Furthermore, the influence of SWNT addition on the thermal stability of graphite in mixtures of SWNT/graphite at different proportions was investigated. The graphite stability decreased with the increased of SWNT content in the overall range of composition. This behavior could be due to the close contact between these carbonaceous species as determined by SEM analysis.

High incidence of contaminating maternal cell overgrowth in human placental mesenchymal stem/stromal cell cultures: A systematic review

Placenta is a readily accessible translationally advantageous source of mesenchymal stem/stromal cells (MSCs) currently used in cryobanking and clinical trials. MSCs cultured from human chorion have been widely assumed to be fetal in origin, despite evidence that placental MSCs may be contaminated with maternal cells, resulting in entirely maternally derived MSC cultures. To document the frequency and determinants of maternal cell contamination in chorionic MSCs, we undertook a PRISMA-compliant systematic review of publications in the PubMed, Medline, and Embase databases (January 2000 to July 2013) on placental and/or chorionic MSCs from uncomplicated pregnancies. Of 147 studies, only 26 (18%) investigated fetal and/or maternal cell origin. After excluding studies that did not satisfy minimal MSC criteria, 7 of 15 informative studies documented MSC cultures as entirely fetal, a further 7 studies reported cultured human chorionic MSC populations to be either maternal (n=6) or mixed (n=1), whereas 1 study separately cultured pure fetal and pure maternal MSC from the same placenta. Maternal cell contamination was associated with term and chorionic membrane samples and greater passage number but was still present in 30% of studies of chorionic villous MSCs. Although most studies assume fetal origin for MSCs sourced from chorion, this systematic review documents a high incidence of maternal-origin MSC populations in placental MSC cultures. Given that fetal MSCs have more primitive properties than adult MSCs, our findings have implications for clinical trials in which knowledge of donor and tissue source is pivotal. We recommend sensitive methods to quantitate the source and purity of placental MSCs.

High-yield bacterial expression and structural characterization of recombinant human insulin-like growth factor binding protein-2

The diverse biological activities of the insulin-like growth factors (IGF-1 and IGF-2) are mediated by the IGF-1 receptor (IGF-1R). These actions are modulated by a family of six IGF-binding proteins (ICFBP-1-6; 22-31 kDa) that via high affinity binding to the IGFs (K-D similar to 300-700 pM) both protect the IGFs in the circulation and attenuate IGF action by blocking their receptor access In recent years, IGFBPs have been implicated in a variety of cancers However, the structural basis of their interaction with IGFs and/or other proteins is not completely understood A critical challenge in the structural characterization of full-length IGFBPs has been the difficulty in expressing these proteins at levels suitable for NMR/X-ray crystallography analysis Here we describe the high-yield expression of full-length recombinant human IGFBP-2 (rhIGFBP-2) in Eschericha coli Using a single step purification protocol, rhIGFBP-2 was obtained with >95% purity and structurally characterized using NMR spectroscopy. The protein was found to exist as a monomer at the high concentrations required for structural studies and to exist in a single conformation exhibiting a unique intra-molecular disulfide-bonding pattern The protein retained full biologic activity. This study represents the first high-yield expression of wild-type recombinant human IGFBP-2 in E coli and first structural characterization of a full-length IGFBP (C) 2010 Elsevier Inc. All rights reserved

Fluorene-Based Copolymers Containing Dinaphtho-s-indacene as New Building Blocks for High-Efficiency and Color-Stable Blue LEDs

By incorporating a new building block, 7,7,15,15-tetraoctyldinaphtho-s-indacene (NSI), into the backbone of poly(9,9-dioctylfluorene) (PFO), a novel series of blue light-emitting copolymers (PFO-NSI) have been developed. The insertion of the NSI unit into the PFO backbone leads to the increase of local effective conjugation length, to form low-energy fluorene-NSI-fluorene (FNF) segments that serve as exciton trapping sites, to which the energy transfers from the high-energy PFO segments. This causes these copolymers to show red-shifted emissions compared with PFO, with a high efficiency and good color stability and purity. The best device performance with a luminance efficiency of 3.43 cd . A(-1), a maximum brightness of 6 539 cd . m(-2) and CIE coordinates of (0.152, 0.164) was achieved.

Improved color purity and efficiency by a coguest emitter system in doped red light-emitting devices

We demonstrate red organic light-emitting diodes (OLEDs) with improved color purity and electroluminescence (EL) efficiency by codoping a green fluorescent sensitizer 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1, 1, 7,7-tetramethyl-1H, 5H, 11H-(1)-benzopyropyrano(6,7-8-ij)quinolizin-11-one (C545T) as the second dopant and a red fluorescent dye 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as the lumophore into tris(8-hydroquinoline) aluminum (Alq(3)) host. It was found that the C545 T dopant did not by itself emit but assisted the carrier trapping from the host Alq(3) to the red emitting dopant. The red OLEDs realized by this approach not only kept the purity of the emission color, but also significantly improved the EL efficiency. The current efficiency and power efficiency, respectively, reached 12 cd/A at a current density of 0.3 mA/cm(2) and 10lm/W at a current density of 0.02 mA/cm(2), which are enhanced by 1.4 and 2.6 times compared with devices where the emissive layer is composed of the DCJTB doped Alq(3), and a stable red emission (chromaticity coordinates: x = 0.64, y = 0.36) was obtained in a wide range of voltage. Our results indicate that the coguest system is a promising method for obtaining high-efficiency red OLEDs.

Green light-emitting polyfluorenes with improved color purity incorporated with 4,7-diphenyl-2,1,3-benzothiadiazole moieties

By incorporating 4,7-diphenyl- 2,1,3 benzothiadiazole instead of 2,1,3-benzothiadiazole into the backbone of polyfluorene, we developed a novel series of green light- emitting polymers with much improved color purity. Compared with the state-of-the-art green light-emitting polymer, poly(fluorene-co-benzothiadiazole) (lambda max = 537 nm), the resulting polymers (lambda(max) = 521 nm) showed 10-20 nm blueshifted electroluminescence (EL) spectra and greatly improved color purity because the insertion of two phenylene units between the 2,1,3-benzothiadiazole unit and the fluorene unit reduced the effective conjugation length in the vicinity of the 2,1,3-benzothiadiazole unit. As a result, the resulting polymers emitted pure green light with CIE coordinates of (0.29, 0.63), which are very close to (0.26, 0.65) of standard green emission demanded by the National Television System Committee (NTSC). Moreover, the insertion of the phenylene unit did not affect the photoluminescence (PL) and EL efficiencies of the resulting polymers. PL quantum efficiency in solid films up to 0.82 was demonstrated. Single-layer devices (ITO/PEDOT/ polymer/Ca/Al) of these polymers exhibited a turn-on voltage of 4.2 V, luminous efficiency of 5.96 cd A(-1) and power efficiency of 2.21 lm W-1. High EL efficiencies and good color purities made these polymers very promising for display applications.

Determination of purity and molecular weight of calmodulin by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The purity and molecular weight of calmodulin have been determined by means of matrix-assisted laser desorption/ionization time of flight mass spectrometry, and the results have been discussed. The experimental results demonstrate that this method is high sensitive and rapid as compared with other traditional methods.

Purification of High-quality Plastid DNA from the Brown Alga Laminaria japonica Sporophytes

Extracting DNA from a variety of algae is rather difficult because of high levels of polysaccharides, tannins, and phenolics as these interfere with DNA isolation and downstream applications. High-quality plastid DNA (ptDNA) purification is particularly difficult because of its small proportion in total genomic DNA. This report describes an improved protocol for ptDNA purification that efficiently produces high-quality ptDNA from sporophytes of Laminaria japonica and several other algae. This improved protocol simplifies procedures for ptDNA purification and improves yield to 150-200 mu g of ptDNA per 100 g of frozen algal tissue. Polymerase chain reaction (PCR) amplification of conserved sequences has been used to verify purity of the ptDNA product.

An efficient combination of supercritical fluid extraction and high-speed counter-current chromatography to extract and purify homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler

Supercritical fluid extraction (SFE) was used to extract homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler. The optimization of parameters was carried out using an orthogonal test L-9 (3)(4) including pressure, temperature, dynamic extraction time and the amount of modifier. The process was then scaled up by 100 times with a preparative SFE system under the optimized conditions of 25 MPa, 55 degrees C, 4.0 h and 25% methanol as a modifier. Then crude extracts were separated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/ACN/water (1.8:1.0:1.0:1.2:1.0 v/v). There three homoisoflavonoidal compounds including methylophiopogonanone A 6-aldehydo-isoophiopogonone A, and 6-formyl-isoophiopogonanone A, were successfully isolated and purified in one step. The collected fractions were analyzed by HPLC. In each operation, 140 mg crude extracts was separated and yielded 15.3 mg of methylophiopogonanone A (96.9% purity), 4.1 mg of 6-aldehydo-isoophiopogonone A (98.3% purity) and 13.5 mg of 6-formyl-isoophiopogonanone A (97.3% purity) respectively. The chemical structure of the three homoisoflavonoids are identified by means of ESI-MS and NMR analysis.

One step isolation and purification of liquiritigenin and isoliquiritigenin from Glycyrrhiza uralensis Risch using high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) technique in semi-preparative scale has been successfully applied to the separation of bioactive flavonoid compounds, liquiritigenin and isoliquiritigenin in one step from the crude extract of Glycyrrhiza uralensis Risch. The HSCCC was performed using a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-acetonitrile-water (2:2:1:0.6:2, v/v). Yields of liquiritigenin (98.9% purity) and isoliquiritigenin (98.3% purity) obtained were 0.52% and 0.32%. Chemical structures of the purified liquiritigenin and isoliquiritigenin were identified by electrospray ionization-MS (ESI-MS) and NMR analysis. (c) 2005 Published by Elsevier B.V.

Efficiency and purity control in the preparation of pure and/or aluminum-doped barium ferrites by hydrothermal methods using ferrous ions as reactants

The synthesis of hexagonal barium ferrite (BaFe12O19) was studied under hydrothermal conditions by a method in which a significant amount of ferrous chloride was introduced along side ferric chloride among the starting materials. Though all of the Fe2+ ions in the starting material were converted to Fe3+ ions in the final product, Fe2+ was confirmed to participate differently from the Fe3+ used in the conventional method in the mechanism of forming barium ferrite. Indeed the efficiency of the synthesis and the quality of the product and the lack of impurities such as Fe2O3 and BaFe2O4 were improved when Fe2+ was included. However, the amount of ferrous ions that could be included to obtain the desired product was limited with an optimum ratio of 2:8 for FeCl2/FeCl3 when only 2h of reaction time were needed. It was also found that the role of trivalent Fe3+ could be successfully replaced by Al3+. Up to 50% of their on could be replaced by Al3+ in the reactants to produce Al- doped products. It was also found that the ratio of Fe2+/M3+ could be increased in the presence of Al3+ to produce high quality barium ferrite.

Application of preparative high-speed counter-current chromatography for the separation of flavonoids from the leaves of Byrsonima crassa Niedenzu (IK)

The methanolic extract of the leaves of the medicinal plant Byrsonima crassa (Malpighiaceae) contain flavonoids with antioxidant activity. They were separated in a preparative scale using high-speed counter-current chromatography. The optimum solvent system used was composed of a mixture of ethyl acetate-n-propanol-water (140:8:80 (v/v/v)) and led to a successful separation between monoglucosilated flavonoids (quercetin-3-O-alpha-L-arabinoside, quercetin-3-O-beta-D-galactoside) and the biflavonoid amentoflavone in only 3.5 h. The purities of quercetin-3-O-alpha-L-arabinoside (95 mg), quercetin-3-O-beta-D-galactoside (16 mg) and the biflavonoid amentoflavone (114 mg) were all isolated at purity over 95%. Identification was performed by H-1 NMR, C-13 NMR and UV analyses. (C) 2004 Published by Elsevier B.V.