[en] The rare earth Ce³⁺ and Tb³⁺ ions -doped α-zirconium phosphate [Zr(HPO₄)₂, abbreviated as ZrP] nanosheet phosphors were prepared by direct precipitation process at ambient temperature. The X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence emission and excitation spectra and the fluorescent lifetime measurements were used to characterize the crystal structure, morphology as well as the luminescent properties of the phosphor system. The Ce³⁺ or/and Tb³⁺ ions-doped ZrP system clearly exhibited nanosheet structure, as can be confirmed from their XRD and SEM results. Excited with ultra-violet (UV) light 368 nm, the Ce³⁺/Tb³⁺-codoped ZrP showed intense green emission at 546 nm corresponding to the ⁵D₄→⁷F₅ transition of Tb³⁺. With the increase of Ce³⁺ doping concentration, the luminescent intensity and fluorescence lifetimes of Tb³⁺ were gradually increased. The results manifested that the obvious energy transfer phenomenon from Ce³⁺ to Tb³⁺ happened, and the energy transfer mechanism should be due to the dipole–quadrupole interaction. Moreover, the chromaticity coordinate of ZrP:Ce³⁺,Tb³⁺ nanosheet was also studied, and the emission color can be adjusted from blue-greenish to green by increasing the Ce³⁺ concentration. The ZrP:Ce³⁺,Tb³⁺ nanosheet may be used as a green-light emitting candidate for the optoelectronic devices such as electroluminescence panels or white light-emitting diodes.

[en] Highlights: • The structure of fluorphlogopite was modified by the decrease of layer charge. • Characteristic emission of Eu³⁺ was greatly enhanced as doped to the modified clay. • The emitting color changed from orange-red to red in respect to the original host. • This is a new strategy to enhance the luminescence of inorganic layered materials. - Abstract: In this paper, the lamellar fluorphlogopite was structurally modified by the adjustment of layer charge and the rare earth Eu³⁺ was doped to fluorphlogopite with a subsequent high temperature solid state reaction process. The structural modification involved a preliminary treatment of fluorphlogopite with HNO₃ and oxalic acid to reduce the layer charge density, and part of the charge-reduced fluorphlogopite was converted to a homoionic Na form by ion exchange with NaCl or NaB(C₆H₅)₄. It has been noticed that the interlayer spacing of modified fluorphlogopite is decreased as compared with the original fluorphlogopite due to the ionic radius difference between K⁺ and Na⁺. The photoluminescence study suggests that adjustment of layer charge of fluorphlogopite is beneficial to enhance the luminescence intensity excited with near UV light, and the layered system may be a potential red light component for the use of solid-state lighting and other optoelectronic fields.

[en] Graphical abstract: - Highlights: • PPy/γ-Fe₂O₃ hybrid materials were prepared by sol–gel polymerization in situ. • Different reactant molar ratios resulted in different microstructures of γ-Fe₂O₃ and molecular weights of PPy. • PPy/γ-Fe₂O₃ hybrids had selectivity for NH₃ gases at low temperatures (<100 °C). • The sensing mechanism was suggested to be related to the existence of p–n heterojunctions in the PPy/γ-Fe₂O₃ hybrid material. - Abstract: Polypyrrole (PPy)/γ-Fe₂O₃ hybrid materials were prepared by sol–gel polymerization in situ and characterized by Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), thermogravimetric and differential thermal analysis (TG–DTA) and high-resolution transmission electron microscope (HRTEM). The gas sensitivities in CO, H₂, NH₃, ethanol or acetone atmospheres were determined at 30 °C, 60 °C and 90 °C. FT-IR and XRD patterns suggest that ferric oxide in the hybrids was γ-Fe₂O₃, with a diameter of approximately 5 nm. TG–DTA and HRTEM analyses showed that different reactant molar ratios of pyrrole monomer: Fe(NO₃)₃·9H₂O resulted in different microstructures of γ-Fe₂O₃ and molecular weights of PPy. An increased amount of Fe(NO₃)₃·9H₂O increased the degree of uniformity of the molecular weight of PPy and resulted in a change of γ-Fe₂O₃ microstructure from granular to stick particles. The results of gas sensitivities showed that the PPy/γ-Fe₂O₃ hybrids exhibited high sensitivity to NH₃ at mild operating temperature (<100 °C). Furthermore, the sensing mechanism was also discussed

[en] Cortical and medullary venous signs are defined as the increase and enlargement of cerebral cortical and medullary venous vessels on the susceptibility weighted imaging (SWI). The signs can be used to explore the dynamic evolution of acute ischemic stroke (AIS) after ictus of acute ischemic attack, to assess the peripheral collateral circulation state, to predict the ischemic penumbra, and to evaluate the patients' outcome. We summarized the cortical and medullary venous signs including prominent venous signs, asymmetric prominent cortical venous signs, and deep medullary venous signs on the SWI sequence in AIS, and mainly reviewed the relationships between the signs and collateral circulation, the size of final infarction volume, neurological function, and hemorrhagic transformation related to the prognosis of AIS. (authors)

[en] A method is introduced for open-column photo-induced site-selective immobilization of pH gradients in a layer of PEG-methacrylate in a multi-dimensional microfluidic chip for use in electrophoresis. It has several attractive features: (a) mixtures of fluorescently labelled proteins carbonic anhydrase, catalase and myoglobin in their native state can be separated by pH-gradient isoelectric focusing (IEF) and zone electrophoresis (CZE) using integrated 2D chip electrophoresis; (b) compared to strip packing or monolithic photo-immobilization, it overcomes the shortcomings of free carrier ampholyte-based 2D chip electrophoresis in an easy way; (c) larger amount of sample can be loaded into the open column-mode electrophoresis (d) immobilized pH gradients can be re-used and the chip can be recycled; (e) a multilayer 3D pH gradient is established by a layer-by-layer assembly technique to further increase the separation capacity. In our perception, this strategy has a large potential in microfluidic chip-based separation schemes because of its simplicity, separation power, re-usability, and separation capacity. (author)

[en] In this paper, the blue-light-emitting Sr₂CeO₄ phosphor powders were prepared by hydrothermal combustion reactions and a subsequent sintering process. During the process, the mixed urea and glycine were both used as leavening agent and fuel. The particle crystallization, surface morphology as well as the luminescence intensities of the Sr₂CeO₄ phosphor powders were effectively improved by adjusting the amount of glycine and post-sintering temperatures. The Sr₂CeO₄ phosphor exhibited strong crystallization and well-distributed spherical particle after optimization. Moreover, the intense blue-light emission band with the maximum at 468 nm in the range of 400–600 nm was observed as excited with ultraviolet light 277 nm. In particular, after the precursors were heat-treated at 1100 °C, the samples could be well-excited around 350 nm. The excitation bands were ascribed to the charge transfer from O to Ce, and the enlarged excitation range may facilitate its uses in optoelectronic fields.

[en] In this paper, the red-emitting La₂Ce₂O₇:Eu³⁺ composite nanopowders were successfully prepared via simple solution combustion synthesis (SCS) and surfactant (polyvinyl alcohol)-assisted solution combustion synthesis (PVACS), and characterized by X-ray diffraction, scanning electron microscopy, photoluminescence emission and excitation spectra, as well as fluorescent decay measurements. The X-ray diffraction results suggested the formation of La₂Ce₂O₇ composite solid solution, and the introduction of Eu had little influence on the structure of the composite. The La₂Ce₂O₇:Eu³⁺ composite showed controlled nanopowders (from 10 to 120 nm) with well-distributed morphologies under the assistance of certain amount of surfactant and subsequent heat-treatment process. The photoluminescence measurements indicated that the samples could be efficiently excited with blue light (467 nm), and exhibited the characteristic red emission of Eu³⁺ ion at 616 nm corresponding to the ⁵D₀ →⁷F₂ transition. The optimal concentration of activator Eu³⁺ ion was confirmed at about 15 mol% as the total amount of cations was considered. Moreover, the relative emission intensity, fluorescent lifetime and quantum efficiency of the La₂Ce₂O₇:Eu³⁺ composite powders prepared by PVACS were compared with those achieved by simple SCS and traditional solid state reaction, which further confirmed the merits by PVACS. These results may facilitate the optimized composite nanopowders as a potential candidate for solid state lighting owing to the coincidence of 467 nm excitation light with the emission of InGaN chips in white light-emitting-diodes.

[en] Highlights: • Glycine–modified Carbon dots (G-CDs) with high fluorescent quantum yield (QY = 31%) were prepared by microwave-assisted method. • G-CDs were stability at biological system, and had low cytotoxicity. • Human transferrin (hTf) had one type of binding site with G-CDs, and the fluorescence quenching mode was static quenching process. - Abstract: Luminescent carbon dots (CDs) are new fluorescent materials and widely used in biomedical fields. In this paper, CDs were prepared using citric acid and glycine (denoted G-CDs) by one-step microwave-assisted method and characterized by transmission electron microscopy (TEM), power X-ray diffraction (XRD), nuclear magnetic resonance (¹³CNMR), and Fourier transform infrared (FT-IR). The results showed that glycine was better than PEG200 or hexadecyltrimethyl ammonium bromide (CTAB) as the modification in reaction. The prepared G-CDs had the sizes about 10 nm, high fluorescent quantum yield (QY) up to 31%, and stability at biological system. Moreover, G-CDs had low cytotoxicity. Our results verified that amino group (or secondary amines) had a significant effect on the QY; one-step microwave-assisted method was simple, efficient and green. The further experiments about the interaction of G-CDs with human transferrin (hTf) were also detected. Data showed that there was a strong interaction between G-CDs and hTf, and one type of binding site between them. The quenching mode of fluorescence of hTf with G-CDs was static quenching process.

[en] In this paper, photoinduced protein immobilizations on quartz glass slides utilizing benzophenone as photoinitiator without any photoactive group derivatizations involved were developed. Three different methods mediated by benzophenone were investigated, including protein photo-attachment onto untreated glass surface, protein attachment onto glass surface by reacting with pre-photografted maleic anhydride, and protein photo-attachment onto alkylamino silane functionalized glass surface, respectively. Protein immobilizations were characterized by fluorescence microscopy and atomic force microscopy. The preservation of biological activity after protein photo-attachments was confirmed by immunoassays. Area-defined protein immobilization was also primarily investigated. Comparative studies demonstrated that in respect of immobilization density, coverage homogeneities and photo-localization, protein photocoupling to amino-terminated quartz glass surfaces remarkably outperformed other photoinduced methods, as well as one kind of 3-(triethoxysilyl) propyl isocyanate chemical protein immobilization. The feasibility of this protein photo-immobilization on silicon-based materials is promising for widespread application because of its simplicity and effectiveness.

[en] Highlights: • p-NP reduction is the best at pH 7.6 by Fe(II) species in chloride medium. • Sulfate and its dosage have markedly inhibitory effect on p-NP reduction. • Chloride and its dosage have no obvious effect on p-NP reduction. • Sulfate has selective adsorption on Fe hydroxide. • Sulfate can form surface complexes on Fe hydroxide. -- Abstract: Electron exchange between aqueous Fe(II) and structural Fe(III) of iron minerals has been illustrated for understanding the reduction of nitroaromatic compounds (NAC). However, factors influencing Fe(II)-induced the reduction of NAC still remain elusive. In this paper, p-nitrophenol (1.5 mM) was selected to explore the effects of pH, the stabilizing ligands (Cl⁻, SO₄²⁻) of ferrous ions and the extra addition of iron hydroxide on the reduction of NAC via Fe(II) species. The results indicate that the reduction degree of is much lower in SO₄²⁻ medium than that in Cl⁻ medium at pH 7.6. p-Nitrophenol reduction increased in SO₄²⁻ medium and slightly decreased in Cl⁻ medium when Fe hydroxide was extra added. Cl⁻ strength (0.01–0.1 mol L⁻¹) has no obvious effect on p-NP reduction. SO₄²⁻ species and its dosage have markedly inhibitory effect on p-NP reduction due to the selective adsorption of SO₄²⁻ and the formation of sulphated surface complexes on the fresh Fe hydroxide