Lie ZHAO
,
Fred J. VERMOLEN
,
Jilt SIETSMA
,
Sybr
,
van der ZWAAG
材料科学技术（英文）
The present work analyses the total free energy of the material during the martensitic transformation. A general expression for the martensite fraction as a function of temperature is derived, assuming that the nonchemical free energy is proportional to the volume of martensite. This expression indicates that the temperature-dependent martensite fraction can be predicted once the characteristic transformation temperatures and the relation between the chemical free energy and temperature of the martensite and austenite are known. An advantage of this development is that the proposed equation is valid for all types of relations between the chemical free energy and temperature. This simulation is successfully applied to the martensitic transformation upon further cooling of retained austenite in a low-alloyed TRIP steel, in which the relation between chemical free energy and temperature is quadratic and the fraction is determined from a thermo-magnetic measurement.
关键词:
Thermodynamics
,
null
,
null
,
null
赵秋伶
,
张尤华
,
于晓艳
分析化学
doi:10.11895/j.issn.0253-3820.160029
基于富含胸腺嘧啶(T)DNA适配体对Hg2+的特异性识别和核酸外切酶I(Exo Ⅰ)辅助的信号转换策略,建立了快速检测人尿液中Hg2+的荧光分析方法。固定在微孔板上的DNA适配体特异识别Hg2+后,折叠成稳定的发卡型双链结构,不能被单链特异性的Exo Ⅰ水解,核酸染料SYBR Green I(SG)插入发卡部位产生荧光信号,基于此可实现Hg2+的定量检测。优化后的最佳实验条件为:微孔板包被亲和素浓度为50 mg/L;检测DNA包被浓度为75 nmol/L;使用5×@SG以及1.2μL的Exo Ⅰ。在最佳实验条件下,体系荧光强度与Hg2+浓度的对数呈良好线性关系,线性范围为2-500 nmol/L,检出限为1.5 nmol/L(3σ)。利用本方法检测尿样中的Hg2+,加标回收率为91.2%-95.0%,相对标准偏差(n=5)为2.1%-4.6%。本方法选择性良好,操作简单,用HNO3-KMnO4溶液将尿液中其它形式的汞氧化为Hg2+后,成功实现了尿液中总汞含量的检测。
关键词:
DNA识别
,
核酸外切酶I
,
汞离子
,
信号放大
,
荧光分析
张德蒙
,
娄茹云
,
王雨
,
刘袖洞
,
于炜婷
,
马小军
功能材料
doi:10.3969/j.issn.1001-9731.2016.02.037
利用静电自组装法制备了壳聚糖/siRNA纳米粒,建立了SYBR Gold核酸染料法测定siRNA复合率(CR),并系统性考察了n(N)/n(P)比,壳聚糖分子量(Mw)、脱乙酰度(DD)及制备环境pH值、缓冲液浓度(Bc)对纳米粒siRNA复合率、粒径及表面电位的影响规律.结果表明,siRNA复合率由n(N)/n(P) 0.5时的(18.6±4.0)％快速增大至n(N)/n(P)为2时的(92.9±2.0)％,但随n(N)/n(P)增大复合率不再升高;n(N)/n(P)＜2时,难以形成稳定纳米粒,复合物表面电位为负,n(N)/n(P)由5升至150时,纳米粒粒径由(179.3±5.7) nm增大至(235.5±8.3) nm,表面电位由(17.2±1.3) mV升高至(23.6±0.9) mV.另外,n(N)/n(P) 150时,CR随DD升高而升高,随Bc升高而降低;纳米粒粒径随Mw增大而增大,随DD及缓冲液浓度(Bc)升高而减小;纳米粒表面电位随DD升高而升高,随pH值及Bc升高而降低.n(N)/n(P)比对纳米粒特性及siRNA复合率影响最为显著,调整n(N)/n(P)、Mw、DD、pH值及离子强度可得到siRNA复合率在90％以上,粒径100～300 nm,表面电位15～25 mV的纳米粒.
关键词:
壳聚糖
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小干扰RNA
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核酸染料
,
复合率
