Self-assembled 3D flowerlike Lu2O3 and Lu2O3 : Ln(3+) (Ln = Eu, Tb, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures: Ethylene glycol-mediated hydrothermal synthesis and luminescent properties

Three-dimensional flowerlike Lu2O3 and Lu2O3:Ln(3+) (Ln = Eu, Th, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures have been successfully synthesized via ethylene glycol (EG)-mediated hydrothermal method followed by a subsequent heat treatment process. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, elemental analysis, inductively coupled plasma atomic absorption spectrometric analysis, ion chromatogram analysis, X-ray photoelectron spectra, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. Hydrothermal temperature, EG, and CH3COONa play critical roles in the formation of the lutetium oxide precursor microflowers. The reaction mechanism and the self-assembly evolution process have been proposed. The as-formed lutetium oxide precursor could transform to Lu2O3 With their original flowerlike morphology and slight shrinkage in the size after postannealing process.

The study of novel Fe3O4@gamma-Fe2O3 core/shell nanomaterials with improved properties

The surface structure of the iron oxide nanoparticles obtained by the co-precipitation method has been investigated, and a thin layer of alpha-FeOOH absorbed on surface of the nanoparticle is confirmed by analyses of Fourier transform infrared (FTIR), X-ray photoelectron spectra (XPS) and surface photovoltage spectroscopy (SPS). After annealed at 400 degrees C, the alpha-FeOOH can be converted to gamma-Fe2O3. The simple-annealed procedure resulted in the formation of Fe3O4@gamma-Fe2O3 core/shell structure with improved stability and a higher magnetic saturation value, and also the simple method can be used to obtain core/shell structure in other similar system.

Synthesis and characterization of nano-scale Terbium (III)-trimesic acid (TMA)-1,10-phenanthroline(phen) luminescent complex

The nano-scale luminescent complex of Terbium(III)-trimesic acid (TMA)-1,10-phenanthroline(phen) was successfully synthesized by co-precipitation method in this paper. The chemical formula of the synthesized complex was speculated to be Tb(TMA)(phen)(0.0125)center dot 5H(2)O by elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and Fourier-transform infrared spectroscopy (FTIR). XRD pattern of Tb(TMA)(phen)(0.0125)center dot 5H(2)O indicated that it was a new crystalline complex since the diffraction angle, diffraction intensity and the distance of crystal plane were all different from those of the two ligands. TG curve proved that the synthesized nano-scale luminescent complex was stable in the range from ambient temperature to 464 degrees C in air. TEM images showed that the complex was spherical shape with an average size of 40 nm.

Facile Surfactant- and Template-Free Synthesis and Luminescent Properties of One-Dimensional Lu2O3:Eu3+ Phosphors

Uniform Lu2O3:Eu3+ nanorods and nanowires have been successfully prepared through a simple solution-based hydrothermal process followed by a subsequent calcination process without using any surfactant, catalyst, or template. On the basis of X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and Fourier transform infrared spectroscopy results, it can be assumed that the as-obtained precursors have the structure formula of Lu4O(OH)(9)(NO3), which is a new phase and has not been reported. The morphology of the precursors could be modulated from nanorods to nanowires with the increase of pH value using ammonia solution. The as-formed precursors could transform to cubic Lu2O3:Eu3+ with the same morphology and a slight shrinkage in size after an annealing process, Both the Lu2O3:Eu3+ nanorods and nanowires exhibit the strong red emission corresponding to the D-5(0)-F-7(2) transition of the Eu3+ ions under UV light excitation or low-voltage electron beam excitation.

Preparation of SrAl2O4:Eu2+, Dy3+ fibers by electrospinning combined with sol-gel process

One-dimensional SrAl2O4:Eu2+, Dy3+ fibers were fabricated by a simple electrospinning combined with sol-gel process. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence were used to characterize the fibers. The results show that the phase structure of SrAl2O4:Eu2+, Dy3+ belongs to a monoclinic one, the composite fibers and fibers calcined at high temperature remain the original one-dimensional texture, and the SrAl2O4:Eu2+, Dy3+ was a green emission. (C) 2010 Elsevier Inc. All rights reserved.

Synthesis of Titanate-Based Nanotubes for One-Dimensionally Confined Electrical Properties

Structural tailoring for dimensionally confined electrical properties is fundamentally important for nanodevices and the relevant technologies. Titanate-based nanotubes were taken as a prototype one-dimensional material to study. First, Na0.96H1.04Ti3O7 center dot 3.42H(2)O nanotubes were prepared by a simple hydrothermal condition, which converted into Na0.036H1.964Ti3O7 center dot 3.52H(2)O nanotubes by a subsequent acidic rinsing. Systematic sample characterization using combined techniques of X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, electron paramagnetic resonance, Fourier transform infrared spectroscopy, elemental analyses, and alternative current impedance indicated that both nanotubes possessed a scrolled trititanate-type structure with the (200) crystal face predominant on the tube surface. With increasing temperature, both nanotubes underwent a continuous dehydration process, which however imposed different impacts oil the structures and electrical properties, depending on the types of the nanotubes

"Green synthesis" of monodisperse Pt nanoparticles and their catalytic properties

A green synthetic strategy to prepare monodisperse Pt nanoparticles was reported. Aminodextran acted as the reductive and protective agents, and Pt nanoparticles were characterized by UV/vis spectroscopy (UV-vis), Pt nanoparticles were conveniently obtained at one step. transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). By changing the initial molar ratio of arninodextran to platinum precursor, Pt nanoparticles with different size were obtained. Amino groups of aminodextran could absorb on Pt nanoparticles surfaces and serve as a very good stabilizer. However, dextran without amino groups could not effectively stabilize Pt nanoparticles and aggregation of Pt nanoparticles were obtained. Catalytic activity of these Pt nanoparticles for the electron-transfer reaction between hexacyanoferrate (III) ions and thiosulfate ions was also studied, and they showed good catalytic efficiency.

Spherical SiO2@GdPO4 : Eu3+ core-shell phosphors: Sol-gel synthesis and characterization

Nanocrystalline GdPO4 : Eu3+ phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by Pechini sol-gel method, resulting in the formation of core-shell structured SiO2@GdPO4 : Eu3+ particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), time-resolved PL spectra and lifetimes were used to characterize the core-shell structured materials. Both XRD and FT IR results indicate that GdPO4 layers have been successfully coated on the SiO2 particles, which can be further verified by the images of FESEM and TEM. Under UV light excitation, the SiO2@GdPO4: Eu3+ phosphors show orange-red luminescence with Eu(3+)sD(0)-F-7(1) (593 nm) as the most prominent group. The PL excitation and emission spectra suggest that an energy transfer occurs from Gd3+ to Eu3+ in SiO2@GdPO4: Eu3+ phosphors. The obtained core-shell phosphors have potential applications in FED and PDP devices.

Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ particles: Polyol-mediated synthesis and luminescent properties

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodo-luminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10-20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb3+-doped CaWO4 particles show the characteristic emission of Tb3+ D-5(4)-F-7(J) (J=6-3) transitions due to an energy transfer from WO42- groups to Tb3+.

Studies on lignan constituents from Schisandra chinensis (Turcz.) Baill. fruits using high-performance liquid chromatography/electrospray ionization multiple-stage tandem mass spectrometry

A reversed-phase high-performance liquid chromatography-diode array detector-electrospray ionization multiple-stage tandem mass spectrometry (RP-HPLC-DAD-ESl-MSn) method has been developed for the detection and analysis of lignan constituents in the methanol extract from the fruits of Schisandra chinensis (Turcz.) Baill. RP-HPLC-DAD-ESI-MSn and electrospray ionization Fourier transform ion cyclotron resonance multiple-stage tandem mass spectrometry (ESI-FT-TCR-MSn) have been applied to investigate the characteristic product ions of four lignan reference compounds. Then, the logical fragmentation pathways of the lignans have been proposed. By comparing the retention time (t(R)) of HPLC, the ESI-MSn data and the structures of analyzed compounds with the data of reference compounds and in the literature, 11 peaks in HPLC have been unambiguously identified and another 5 peaks have been tentatively identified or deduced. Also, in the present paper, the extracted ion chromatograms (EIC) have been used to analyze the lignan isomers. The experimental results demonstrate that RP-HPLC-DAD-ESI-MSn is a specific and useful method for the identification of the lignan constituents and their isomers.

pH-dependent protein conformational changes in albumin : gold nanoparticle bioconjugates: A spectroscopic study

The conformational changes of bovine serum albumin (BSA) in the albumin:gold nanoparticle bioconjugates were investigated in detail by various spectroscopic techniques including UV-vis absorption, fluorescence, circular dichroism, and Fourier transform infrared spectroscopies. Our studies suggested that albumin in the bioconjugates that was prepared by the common adsorption method underwent substantial conformational changes at both secondary and tertiary structure levels. BSA was found to adopt a more flexible conformational state on the boundary surface of gold nanoparticles as a result of the conformational changes in the bioconjugates. The conformational changes at pH 3.8, 7.0, and 9.0, which corresponded to different isomeric forms of albumin, were investigated, respectively, to probe the pH effect on the conformational changes of BSA in the bioconjugates. The results showed that the pH of the medium influenced the changes greatly and that fluorescence and circular dichroism studies further indicated that the changes were larger at higher pH.

Effect of main-chain rigidity on the phase transitional behavior of comblike polymers

The influence of the rigidity of polymer backbones on the side-chain crystallization and phase transition behavior was systematically investigated by a combination of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), and high-resolution solid-state nuclear magnetic resonance spectroscopy (NMR). DSC investigation indicated that the crystallization number of alkyl carbon atoms of the side chains grafted onto the rigid polymer backbone, poly(p-benzamide) (PBA), is much lower than that of the alkyl carbon atoms of the side chains grafted onto the flexible polymer backbone, poly(ethyleneimine) (PEI), implying that the conformational state of the polymer backbones has a strong effect on the side-chain crystallization behavior in comblike polymers. WAXD and FTIR results proved that these two comblike polymers pack into hexagonal (PBA18C) and orthorhombic (PEI18C) crystals, respectively, depending on the adjusting ability of the polymer backbones for particular conformational states. It was also found that the presence of the crystalline-amorphous interphase (delta = 31.6 ppm) in PBA18C detected by solid-state C-13 NMR spectroscopy can be attributed to the rigid PBA backbone, which restricts the mobility of the alkyl side chains.

Deposition of GdVO4 : Eu3+ nanoparticles on silica nanospheres by a simple sol-gel method

The deposition and coating of GdVO4: Eu3+ nanoparticles on spherical silica was carried out using a simple sol - gel method at low temperature. The GdVO4: Eu3+-coated silica composites obtained were characterized by differential thermal analysis (DTA), thermogravimetric (TG) analysis, x-ray diffraction (XRD), Fourier-transform IR spectroscopy (FT-IR), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), photoluminescence spectra, and kinetic decay. It is found that the similar to 5 nm GdVO4: Eu3+ nanoparticles coating the silica spheres are crystal in the as-prepared samples and the crystallinity increases with increasing annealing temperature. The composites obtained are spherical in shape with an average size of 100 nm. The GdVO4: Eu3+ nanoparticles are linked with silica cores by a chemical bond. The photoluminescence spectra of the obtained GdVO4: Eu3+-coated silica composites are similar to those of the bulk GdVO4: Eu3+ phosphors. The strongest peak is near 617 nm, which indicates that Eu3+ is located in the low symmetry site with non-inversion centre.

Evaluation of different culture conditions for high-level soluble expression of human cyclin A(2) with pET vector in BL21 (DE3) and spectroscopic characterization of its inclusion body structure

In this paper, we evaluated various parameters of culture condition affecting high-level soluble expression of human cyclin A, in Escherichia coli BL21(DE3), and demonstrated that the highest protein yield was obtained using TB(no glycerol) + 0.5% glucose medium at 25 degrees C. By single immobilized metal ion affinity chromatography, we got highly purified human cyclin A(2) with a yield ranged from 20 to 30 mg/L. By amyloid-diagnostic dye ThT binding and Fourier transform infrared spectroscopy, we observed a significant decrease in alpha-helix content and an increase in beta-sheet structure in cyclin A(2) inclusion body in comparison to its native protein, and confirmed the resemblance of the internal organization of cyclin A(2) inclusion body and amyloid fibrils.

Preparation and properties of a reactive type nonionic surfactant grafted linear low density polyethylene

A reactive type nonionic surfactant, monostearic acid monomaleic acid glycerol diester (MMGD) was synthesized in our laboratory. Grafting-copolymerization of linear low density polyethylene ( LLDPE) with MMGD was carried out by using beta ray irradiation in air in a twin-screw extruder. Evidence of the grafting of MMGD as well as its extent was determined by Fourier-transformed infrared (FT-IR) spectroscopy. The effects of monomer concentration, reaction temperature and screw run speed on degree of grafting were studied systematically. The thermal behavior of LLDPE-g-MMGD was investigated by using differential scanning calorimety ( DSC). Compared with neat LLDPE, the crystallization temperature ( Tc) of LLDPE-g-MMGD increased about 3 degrees C, and the melting enthalpy (Delta H-m) decreased with increase of MMGD content. It showed that the grafted MMGD monomer onto LLDPE acted as a nucleating agent. The tensile properties and light transmission of blown films were determined. Comparing with neat LLDPE film, no obvious changes could be found for the tensile strength, elongation at break and right angle tearing strength of LLDPE-g-MMGD film. The wettability is expressed by the water contact angle. With an increasing percentage of MMGD, the contact angles of water on film surface of LLDPE- g-MMGD decrease monotonically.