喷雾热解法制备球形SrAl_2O_4:Eu,Dy长余辉发光材料

采用喷雾热解两段法制备了SrAl2O4:Eu,Dy长余辉发光材料,利用SEM、荧光长余辉亮度测试、F-4500荧光分光光度等方法分析了不同制备工艺条件下SrAl2O4:Eu,Dy发光材料的形貌、余辉性能以及光谱性能的变化。采用喷雾热解两段法可制备出余辉性能良好的球形SrAl2O4:Eu,Dy长余辉发光材料。前驱体溶液浓度、热解温度、添加剂对产物的形貌、粒度分布、发光性能有较大影响。较之高温固相法,喷雾热解法制备的SrAl2O4:Eu,Dy具有合成温度低、发光性能好、形貌好、粒度分布窄等优点。     

A Mild and Highly Efficient Catalyst for Beckmann Rearrangement, BF3·OEt2

BF₃·OEt₂ (Boron trifluoride etherate), an inexpensive and commercially easily available Lewis acid stoichiometrically employed for Beckamann rearrangement in general, was now found to efficiently catalyze Beckmann rearrangement of ketoximes into their corresponding amides (up to 99% yield) in anhydrous acetonitrile under reflux temperature.     

Detection of cortisol at a gold nanoparticle|Protein G-DTBP-scaffold modified electrochemical immunosensor

An ultrasensitive electrochemical immmunosensor was demonstrated to be capable of detecting the hormone cortisol down to concentrations as low as 16 pg mL(-1). In addition, the immunosensor displayed a sensitivity of 1.6 μA pg(-1) mL(-1) and a linear range up to ～2500 pg mL(-1) of cortisol. This immunosensor was constructed based on a Au nanoparticle|dimethyl 3,3'-dithiobispropionimidate·2HCl (DTBP)-Protein G scaffold-modified Au electrode. In this work, the Au nanoparticles were used to increase the electrochemically active surface area by 28% (with a standard deviation of 3%) to enhance the quantity of the Protein G scaffold on the electrode. Thiolation of Protein G by DTBP aided in avoiding the confirmation change of Protein G, while this Protein G-DTBP component offered an orientation-controlled immobilisation of the capture antibody on the Au electrode. In this immunosensor, a monoclonal anti-cortisol capture antibody was optimally aligned by the scaffold before a competitive immunoassay between sample cortisol and a horseradish peroxidase-labelled cortisol conjugate was conducted. For quantitative analysis, square wave voltammetry was used to monitor the reduction current of benzoquinone produced from a horseradish peroxidase catalysed reaction. The improved analytical performance of our immunosensor was attributed to the synergetic effect of Au nanoparticles and the Protein G-DTBP scaffold.     

Electrocatalytic detection of phenolic estrogenic compounds at NiTPPS|carbon nanotube composite electrodes

Assemblies of closed nanoparticles have focused interest because they exhibit new optical and chemical properties. The use of a 1D covalent strategy for quantum dots-assemblies has been proposed in this work as novelty. It was studied the effect of use different dithiols, including aromatic and aliphatic dithiol compounds, on the formation of QDs-assemblies in order to establish the influence of the linker's structure on the geometry of the assemblies, and hence on their properties. As a second part of the work, the changes on analytical response to analytes thanks to the formation of QDs-assemblies when dithiols are added were studied for firs time. For this study, some biogenic amines were selected as target analytes. We observed an improvement of 2.7–4 times in the sensitivity, expressed as slope of the calibration graph, when the dithiols were added to the system obtaining QDs-assemblies.     

Rhodamine hydrazone derivatives as Hg2+ selective fluorescent and colorimetric chemosensors and their applications to bioimaging and microfluidic system

In this paper, we report new rhodamine hydrazone derivatives bearing thiol and carboxylic acid groups as selective fluorescent and colorimetric chemosensors for Hg(2+). The ring-opening process of spirolactam enables the large fluorescent enhancement and colorimetric change upon the addition of Hg(2+). The sample containing Hg(2+) was mixed with one of the chemosensors in a microchannel where the sensor was examined using confocal laser scanning microscopy. A plot of the fluorescent intensities of both chemosensors versus the log concentration of Hg(2+) exhibited a linear response (r(2)=0.95) in the range of 1 nM-1 μM, and the detection limits were 1 nM and 4.2 nM, respectively. Both chemosensors also enable the visualization of Hg(2+) accumulated in the nematode Caenorhabditis elegans previously exposed to nanomolar concentrations of Hg(2+).     

A novel Surface Plasmon Resonance enhanced Total Internal Reflection Ellipsometric application: electrochemically grafted isophthalic acid nanofilm on gold surface

The scope of this study is to modify a Surface Plasmon Resonance (SPR) sensor slide with isophthalic acid to evaluate the possible application on the detection of copper(II) ions in aqueous media by total internal reflection ellipsometry. A gold sensor surface was modified by an electrochemical diazonium reduction modification method. The modified surfaces are characterized with cyclic voltammetry (CV) and ellipsometry. Isophthalic acid monolayer modified gold slides were used for in situ detection of aqueous Cu(2+) solution with the SPR enhanced total internal reflection ellipsometry (SPRe-TIRE) technique. Layer formation, pH dependency of adsorption, sensor response of the SPRe-TIRE and isothermal kinetic parameters were examined. A high dependency on the number of CV cycles in the monolayer-multiple layer transition was observed. The suggested sensor gave a linear response over a wide range of Cu(2+) concentrations. It was also reported that adsorption on the SPRe-TIRE sensor gave Langmuir adsorption model behavior.     

Propargylamine synthesis by copper-catalyzed oxidative coupling of alkynes and tertiary amine N-oxides

An efficient method for synthesizing N,N-dimethylpropargylamines is described. The synthesis exploited the Cu(II)-catalyzed oxidative alkynylation reaction of trimethylamine N-oxides with alkynes in the absence of external oxidant. Both aromatic and aliphatic alkynes were utilized to achieve the corresponding products in moderate to excellent yields. The reaction conditions tolerated ester, hydroxy, and aldehyde groups.     

Helium mediated deposition: modeling the He-TiO2(110)-(1×1) interaction potential and application to the collision of a helium droplet from density functional calculations

This paper is the first of a two-part series dealing with quantum-mechanical (density-functional-based) studies of helium-mediated deposition of catalytic species on the rutile TiO(2)(110)-(1×1) surface. The interaction of helium with the TiO(2)(110)-(1×1) surface is first evaluated using the Perdew-Burke-Ernzerhof functional at a numerical grid dense enough to build an analytical three-dimensional potential energy surface. Three (two prototype) potential models for the He-surface interaction in helium scattering calculations are analyzed to build the analytical potential energy surface: (1) the hard-corrugated-wall potential model; (2) the corrugated-Morse potential model; and (3) the three-dimensional Morse potential model. Different model potentials are then used to study the dynamics upon collision of a (4)He(300) cluster with the TiO(2)(110) surface at zero temperature within the framework of a time-dependent density-functional approach for the quantum fluid [D. Mateo, D. Jin, M. Barranco, and M. Pi, J. Chem. Phys. 134, 044507 (2011)] and classical dynamics calculations. The laterally averaged density functional theory-based potential with an added long-range dispersion interaction term is further applied. At variance with classical dynamics calculations, showing helium droplet splashing out of the surface at impact, the time evolution of the macroscopic helium wave-function predicts that the helium droplet spreads on the rutile surface and leads to the formation of a thin film above the substrate. This work thus provides a basis for simulating helium mediated deposition of metallic clusters embedded within helium nanodroplets.     

Thermo-responsive monodisperse core-shell microspheres with PNIPAM core and biocompatible porous ethyl cellulose shell embedded with PNIPAM gates

A series of size-controllable hierarchically nanostructured magnetic hollow spheres (MHS) (250-2330 nm) have been fabricated by using the hard-template method involving the coprecipitation of ferrite precursor over the pre-synthesized polystyrene spheres with varied sizes under organic solvent-free conditions followed calcinations. The SEM, TEM and HRTEM results indicate that the primary nanoparticles constructing hierarchically nanostructured MHS clearly show the template sphere size-dependent changes in morphologies and stacking modes from disorderly stacked globular and nanorodlike mixed particles, to orderly perpendicularly oriented nanorodlike particles, and to compact horizontally arranged nanospindle particles as the template size is increased. The N(2) adsorption-desorption data reveal that the MHS spheres have a high BET surface area (48-83 m(2)/g) and large pore volumes (0.37-0.66 cc/g). The vibration sample magnetization analysis shows that the MHS spheres have moderate magnetization saturation of 24-37 emu/g. The adsorption results show that the BSA adsorbance is greatly affected by the varied morphologies and stacking modes of primary nanoparticles constructing the MHS spheres and the maximum adsorption occurs on the MHS spheres mainly comprised of perpendicularly oriented nanorodlike primary particles.     

Patterned polymeric multilayered assemblies through hydrogen bonding and metal coordination

Patterned polymeric multilayered assemblies were formed using a combination of metal coordination and hydrogen bonding interactions. We proved that the hydrogen bonding interaction between diamidopyridine and thymine can be employed for polymeric multilayer assemblies. We then combined this strategy along with a second supramolecular interaction, metal coordination. These interactions proved to be orthogonal to one another on the surface, making each discrete region individually responsive to external stimuli.