Dy3+含量对Eu2+,Dy3+共掺高硅氧发光玻璃发光性能的影响

通过控制Dy3+的掺杂浓度,制备出了不同浓度的Eu2+,Dy3+单掺和共掺高硅氧发光玻璃,测试其激发和发射光谱,讨论了Dy3+浓度对Eu2+,Dy3+共掺样品发光性质的影响。结果表明,Eu2+,Dy3+共掺高硅氧发光玻璃中存在Dy3+向Eu2+的无辐射能量传递现象,且Dy3+的引入会使高硅氧发光玻璃中Eu—O的共价作用减弱,造成Eu2+发射峰蓝移;随着Dy3+浓度的增加,Dy3+→Eu2+能量传递增强,Eu2+发光增强;Dy3+含量继续增加,则Dy3+发光出现浓度猝灭,且Dy3+→Eu2+能量传递减弱。     

微流控制备单分散微米级SiO2微球

采用软模板法制备出了聚二甲基硅氧烷微流控装置。利用该装置讨论了正硅酸乙酯和氨水的用量分别对反应体系凝胶化时间的影响,确定了制备SiO2微球的优化反应体系,即二甲基乙酰胺、正硅酸乙酯和氨水的体积比为8∶4∶1,实验所需的反应温度为60 ℃。实验发现:在微流体通道中,分散相的流速越大,粒径越大;连续相流速越大,粒径越小。因此,通过控制微流控装置中分散相和连续相的流速制备了粒径40~220 m的单分散SiO2微球,并对其形貌进行表征。光学显微镜和粒径分析均表明所制备的SiO2微球球形度高,单分散性好。     

介孔碳材料对蛋白质的吸附行为

用紫外分光光度法,找出介孔碳材料对蛋白质的最佳吸附条件,并测定出该介孔碳材料对溶菌酶的最大吸附量。主要从3方面研究介孔碳材料对蛋白质吸附行为的影响。分别是介孔碳材料对蛋白质吸附行为随接触时间的变化产生的影响,pH值的改变对介孔碳材料吸附蛋白质行为的影响,以及介孔碳材料的量的改变对蛋白质吸附行为随接触时间的变化产生的影响。结果表明,当溶菌酶溶液的初始浓度为210μm ol/L,pH值为11.0,接触时间为96h时介孔碳材料对蛋白质即可达到吸附饱和。该介孔碳材料在最佳条件下对溶菌酶的最大吸附量为27.32μm ol/g,表现出优越的溶菌酶吸附性能。     

The mechanism for negative photochromism of spiropyran in silica

The mechanism for negative photochromism of spiropyran in silica was investigated. Prior to our study, the chemical origin of the high thermal stability of the photomerocyanine form (PMC‐form) dispersed in perhydropolysilazane (PHPS), which is converted to silica at ambient temperature, had been investigated. The high thermal stability of the PMC‐form is attributed to the protonated PMC‐form (H???PMC‐form), which is produced by intermolecular hydrogen bonding between oxide anions generated by the cleavage of the C ? O bonds and the partially uncondensed Si ? OH and O ? H bonds of silica. Furthermore, the H???PMC‐form could be thermally isomerized from the SP‐form without UV light irradiation. This specific phenomenon is caused by the so‐called negative photochromism. In this study, we proposed a mechanism for negative photochromism according to the relationship of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The relationship between the HOMOs was determined using cyclic voltammetry (CV) and ultraviolet photoelectron spectroscopy (UPS). On the other hand, the relationship between the LUMOs was determined from the respective optical bandgap. As a result, the HOMO level of H???PMC‐form was ?6.1 eV and that of SP‐form was ?5.3 eV. Accordingly, the thermodynamic stabilization of H???PMC‐form was attributed to the thermal isomerization through negative photochromism from the SP‐form. Copyright © 2011 John Wiley & Sons, Ltd.     

Ultrasound-assisted synthesis of Li-rich mesoporous LiMn2O4 nanospheres for enhancing the electrochemical performance in Li-ion secondary batteries

The hierarchically structured mesoporous LiMn₂O₄ (LMO) nanospheres were synthesized using a template-free self-assembly process that was coupled with ultrasound (U). The ultrasound technique suggested here is very powerful for controlling an ordered nanostructure and improving crystallinity with large single-crystalline domains. Owing to the hierarchical mesoporous structure and high crystallinity, U-LMO provides an excellent rate capability and cycle stability with a capacity retention of more than 98% up to 50 cycles at a 0.2 C rate. Here, we demonstrate that mesoporous U-LMO nanospheres were fabricated to enhance the electrochemical performance and protect it from structurally significant collapsing because of high crystallinity.     

Electrodeposition of mesoporous ruthenium oxide using an aqueous mixture of CTAB and SDS as a templating agent

Mesoporous RuO₂ films were electrochemically fabricated on ITO-coated glass substrate from aqueous ruthenium chloride (RuCl₃·nH₂O) solution. To achieve highly stable mesoporous structure, an aqueous mixture of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) was used as a templating agent.The mesoporous structure was confirmed by small angle X-ray diffraction (SAXRD) and transmission electron microscopy (TEM). The addition of small amount (10wt%) of CTAB significantly improved the stability of porous structure. The crystallinity of synthesized RuO₂ thin film was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Specific capacitance of the synthesized films was evaluated by measuring cyclic voltammetry (CV) and charge-discharge curves in 0.5 M H₂SO₄. Compared with non-porous electrode, mesoporous RuO₂ showed higher supercapacitor performance.     

Preparation of Bifunctional Mesoporous Silica Nanoparticles by Orthogonal Click Reactions and Their Application in Cooperative Catalysis

The synthesis of bifunctional mesoporous silica nanoparticles is described. Two chemically orthogonal functionalities are incorporated into mesoporous silica by co‐condensation of tetraethoxysilane with two orthogonally functionalized triethoxyalkylsilanes. Post‐functionalization is achieved by orthogonal surface chemistry. A thiol–ene reaction, Cu‐catalyzed 1,3‐dipolar alkyne/azide cycloaddition, and a radical nitroxide exchange reaction are used as orthogonal processes to install two functionalities at the surface that differ in reactivity. Preparation of mesoporous silica nanoparticles bearing acidic and basic sites by this approach is discussed. Particles are analyzed by solid state NMR spectroscopy, elemental analysis, infrared‐spectroscopy, and scanning electron microscopy. As a first application, these particles are successfully used as cooperative catalysts in the Henry reaction.     

Highly specific revelation of rat serum glycopeptidome by boronic acid-functionalized mesoporous silica

Although the specific profiling of endogenous glycopeptides in serum is highly inclined towards the discovery of disease biomarkers, studies on the endogenous glycopeptides (glycopeptidome) have never been conducted because of several factors. These factors include the high dynamic range of serum proteins, the inadequacy of traditional sample preparation techniques in proteomics for low-molecular-weight (LMW) proteins, and the relatively low abundances of glycopeptides. Boronic acid-functionalized mesoporous silica was synthesized in this study to overcome the limitations of the state-of-the-art methods for glycopeptidome research. The boronic acid-functionalized mesoporous silica exhibited excellent selectivity by analyzing glycopeptides in the mixture of glycopeptides/non-glycopeptides at molar ratio of 1:100, extreme sensitivity (the limit of detection was at the fmol level), good binding capacity (40 mg g⁻¹), as well as the high post-enrichment recovery of glycopeptides (up to 88.10%). The as-prepared material possessing both glycopeptide-suitable pore size and glycopeptide-specific selectivity has shown special capability for enriching the endogenous glycopeptides. Fifteen unique glycosylation sites mapped to 15 different endogenous glycopeptides were identified in rat serum. The established protocol revealed for the first time the rat serum glycopeptidome.     

Mesoporous carbon amperometric glucose sensors using inexpensive,commercial methacrylate-based binders

Two ordered, soft-templated mesoporous carbon powders with cubic and hexagonal framework structure and four different commercial, low cost methacrylate-based polymer binders with widely varying physical properties are investigated as screen printed electrodes for glucose sensors using glucose oxidase and ferricyanide as the mediator. Both the chemistry and concentration of the binder in the electrode formulation can significantly impact the performance. Poly(hydroxybutyl methacrylate) as the binder provides hydrophilicity to enable transport of species in the aqueous phase to the carbon surface, but yet is sufficiently hydrophobic to provide mechanical robustness to the sensor. The current from the mesoporous carbon electrodes can be more than an order of magnitude greater than for a commercial printed carbon electrode (Zensor) with improved sensitivity for model glucose solutions. Even when applying these sensors to rabbit whole blood, the performance of these glucose sensors compares favorably to a standard commercial glucose meter with the lower detection limit of the mesoporous electrode being approximately 20 mg dL⁻¹ despite the lack of a separation membrane to prevent non-specific events; these results suggest that the small pore sizes and high surface areas associated with ordered mesoporous carbons may effectively decrease some non-specific inferences for electrochemical sensing.     

Photocatalytic Activity of Fe and Ce Co‐doped Mesoporous TiO2 Catalyst under UV and Visible Light

The catalysts of un‐doped, single‐doped and co‐doped mesoporous titanium dioxide (MTiO₂) were prepared by a template method with tetrabutyltitanate (Ti(OC₄H₉)₄) as a Ti source material and Pluronic P123 as a template. The photo‐absorbance of the obtained catalysts was measured by UV‐vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange (MO) (50 mg/L) in an aqueous solution. It was shown that the co‐doped MTiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The effect of Fe and Ce co‐dopants on the material properties was investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption‐desorption isotherm measurement. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m²/g. The photocatalytic activity of MTiO₂ co‐doped with Fe and Ce was markedly improved due to the synergistic actions of the two dopants.