基于上转换信标探针构建信号放大近红外激发荧光生物传感器用于microRNA检测

基于Na YF_(4):Yb^(3+),Tm^(3+)@Na YF_4上转换纳米颗粒(Upconversion nanoparticles,UCNPs)和DNA催化发夹组装(Catalytic hairpin reaction,CHA)技术构建近红外激发(Near-infrared,NIR)荧光生物传感器,用于micro RNA的高灵敏分析。靶标micro RNA-21(mi RNA-21)可与磁珠(Magnetic beads,MBs)表面修饰的发夹H1发生toehold区域介导的链取代反应,发夹H1暴露新的toehold区域与UCNPs表面修饰的发夹H2发生反应,形成H1/H2复合物,同时mi RNA-21被取代并与新的发夹H1反应,此过程将UCNPs固定于MBs表面,而且实现了信号的循环放大。接下来通过磁分离技术,将固定于MBs表面的UCNPs分离出来,在808 nm NIR的激发下产生上转换发光(Upconversion luminescence,UCL),对mi RNA-21的检测范围为0.1~100 nmol/L,检出限为11.3 pmol/L。此外,该荧光生物传感器成功应用于血清样本中mi RNA-21的分析,表明其具有良好的实用性。

Impacts of Melt Spinning and Element Substitution on Electrochemical Characteristics of the La–Mg–Ni-based A₂B₇-Type Alloys

The partial substitution of Zr for La has been performed in order to ameliorate the electrochemical hydrogen storage performances of La–Mg–Ni based A2B7-type electrode alloys. The melt spinning technology was used to prepare the La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x=0, 0.05, 0.1, 0.15, 0.2) electrode alloys. The impacts of the melt spinning and the substituting La with Zr on the structures and the electrochemical hydrogen storage characteristics of the alloys were systemically investigated. The analysis of XRD and TEM reveals that the as-cast and spun alloys have a multiphase structure, composing of two main phases (La, Mg)2Ni7 and LaNi5 as well as a residual phase LaNi2. The electrochemical measurement indicates that both the substitution of Zr for La and the melt spinning ameliorate the electrochemical cycle stability of the alloys dramatically. Furthermore, the high rate discharge ability (HRD) of the as-spun (10 m/s) alloys notably declines with growing the amount of Zr substitution, while it first augments and then falls for the (x=0.1) alloy with rising the spinning rate.

Gaseous and electrochemical hydrogen storage behaviors of nanocrystalline and amorphous Nd-added Mg_2Ni-type alloys

Melt spinning technology was used to prepare the Mg2Ni-type(Mg24Ni10Cu2)100-xNdx(x = 0, 5, 10, 15,20) alloys in order to obtain a nanocrystalline and amorphous structure.The effects of the spinning rate on the structures and gaseous and electrochemical hydrogen storage behaviors of the alloys were investigated.The analysis of X-ray diffraction(XRD), transmission electron microscope(TEM), and scanning electron microscope(SEM) linked with energy-dispersive spectroscopy(EDS)reveals that all the as-cast alloys hold a multiphase structure, involving the main phase Mg2 Ni and some secondary phases such as Mg6 Ni, Nd5Mg41, and Nd Ni.The as-spun Nd-free alloy displays an entire nanocrystalline structure,whereas the as-spun Nd-added alloys hold a nanocrystalline and amorphous structure, and the amorphization degree visibly increases with the spinning rate increasing.The melt spinning ameliorates the hydrogen storage performances of the alloys dramatically.When the spinning rate rises from 0(the as-cast was defined as the spinning rate of 0 m s-1) to 40 m s-1, the discharge capacity increases from 86.4 to 452.8 m Ah g-1, the S20(the capacity maintain rate at 20 th cycle) value increases from53.2 % to 89.7 %, the hydrogen absorption saturation ratio(Ra5, a ratio of the hydrogen absorption quantity in 5 min to the saturated hydrogen absorption capacity) increases from36.9 % to 91.5 %, and the hydrogen desorption ratio(Rd10,a ratio of the hydrogen desorption quantity in 10 min to the saturated hydrogen absorption capacity) increases from16.4 % to 47.7 % for the(x = 10) alloy, respectively.

醋酸乙烯/乙烯共聚可再分散乳胶粉对硅酸盐水泥基饰面砂浆二次泛白的影响(英文)

目的:采用碱浸出量定量评价醋酸乙烯/乙烯共聚可再分散(VAE)乳胶粉对硅酸盐水泥基饰面砂浆二次泛白的影响,并分析其作用机理。创新点:采用定量化手段评价硅酸盐水泥基饰面砂浆的二次泛白程度。方法:1.采用碱浸出率方法定量评价硅酸盐水泥基饰面砂浆的二次泛白程度;2.采用水浸取法测试硅酸盐水泥基饰面砂浆内部可溶性Ca2+、K+和Na+的含量,p H值及可溶性物质总含量等;3.以硅酸盐水泥基饰面砂浆毛细孔失水速率表征其内部水的蒸发速率。结论:1.硅酸盐水泥基饰面砂浆的碱浸出量可用于定量评价其二次泛白程度,碱浸出量越大,二次泛白越严重;当碱浸出量大于1 g/(m2·h)时,硅酸盐水泥基饰面砂浆会呈现出可见二次泛白;2.Ca2+,K+和Na+等碱离子是导致硅酸盐水泥基饰面砂浆二次泛白的主要根源;3.VAE乳胶粉增加了硅酸盐水泥基饰面砂浆内部Ca2+,K+和Na+等碱离子的含量,并且促进它们向表面迁移,增加了碱浸出率,从而促进二次泛白。