食源性致病菌等温扩增检测技术的研究进展

快速可靠的食源性致病菌检测方法是保障食品安全的关键。然而,传统培养法的检测周期过于冗长,无法适应对时间敏感度较高的现场或在线检测。为此,研究人员开发了多种以快速和高灵敏度为主要特征的等温扩增技术及相应的检测产品,为食源性致病菌的现场或在线检测提供了强有力的技术支撑。该文对环介导等温扩增、滚环扩增、链置换扩增、切口酶信号扩增、核酸外切酶Ⅲ辅助扩增5种等温扩增方法的原理及其优缺点进行了梳理和比较。在此基础上,分析了等温扩增方法在细菌活性识别、非特异性扩增、前处理效率、检测通量4个方面所遇到的共性问题,并结合作者已有工作,提出了解决这些问题的方法或策略。     

Mobility enhancement of strained GaSb p-channel metal oxide semiconductor field-effect transistors with biaxial compressive strain

Various biaxial compressive strained GaSb p-channel metal–oxide–semiconductor field-effect transistors(MOSFETs)are experimentally and theoretically investigated. The biaxial compressive strained GaSb MOSFETs show a high peak mobility of 638 cm~2/V·s, which is 3.86 times of the extracted mobility of the fabricated GaSb MOSFETs without strain.Meanwhile, first principles calculations show that the hole effective mass of Ga Sb depends on the biaxial compressive strain.The biaxial compressive strain brings a remarkable enhancement of the hole mobility caused by a significant reduction in the hole effective mass due to the modulation of the valence bands.     

对称变截面平面曲杆的单元刚度矩阵

本以一种新的思路和做法对变截面曲杆进行单元分析,直接把变截面曲杆作为单元,采用弹性中心法导出了单元刚度矩阵通用公式,确定了截面按余弦规律变化时,轴线分别为圆弧形、抛物线形、半椭圆形平面曲杆的单元刚度矩阵精确式,供结构设计参考使用。     

有机磷酸混合萃取体系的界面化学及动力学控制机制研究

研究了D2EHPA(二(2-乙基己基)磷酸)-M₁PA、M₂PA(长碳链单烷基磷酸酯)-Al³⁺和D2EHPA-MEHPA(单(2-乙基己基)磷酸)-Al³⁺混合萃取体系的界面化学和动力学。结果表明,混合体系界面活性下降,D2EHPA-M₁PA萃取Al³⁺的过程为扩散和化学反应共同控制机制。     

燃烧-中和滴定法测定锌精矿焙砂中的硫

研究了燃烧中和滴定法测定锌精矿焙砂中硫量的测定方法,并对其中的碳、砷、氟元素的干扰问题进行了研究。研究发现样品中碳、砷质量百分数低于1.00%、氟含量低于0.10%时均不影响硫的测定,但氟含量高于0.10%时会对硫的测定产生干扰,而且氟含量越高,对硫的结果影响越大。实验结果表明,方法的相对标准偏差小于3%,与其它经典方法的测定结果比对表明,方法准确、可靠。     

电化学腐蚀法制备STM探针针尖的探究

利用电化学腐蚀法腐蚀高纯钨丝制备了扫描隧道显微镜探针,研究了腐蚀电压、溶液浓度对探针针尖质量的影响.总结出实验室条件下制备探针针尖的最优化条件为:电源电压为18V,NaOH溶液浓度为1mol/L.     

对可用计算器的数学测试的探索与分析

北京市从今年开始高一年级使用人教社出版的数学新教材，我校还参与了“十五”信息技术与课程整合课题研究，使用人教社信息技术与课程整合的试验教材，每个学生一台图形计算器，学生在课上、课下随时随地都可以使用图形计算器，经过一学期的实验，我们希望了解学生对计算器     

Construction of ceo2/rgo/gce electrochemical sensor for the determination of histamine in fishEI北大核心CSCD

By preparing nano-CeO2 (CeO2) and reduced graphene oxide (RGO), an electrochemical sensor based on CeO2/RGO composite was constructed for the detection of histamine. The morphology and structure of the composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical behavior of histamine on the sensor was studied by cyclic voltammetry (CV), and the conditions such as the type proportion and addition amount of the composite scanning rate and buffer pH were optimized. The results showed that the optimal conditions were as follows: The mass ratio was m(CeO2): M(RGO)=1: 0.25, the addition amount of composite material was 10 μL, the scanning rate was 300 mV/s and the pH of buffer solution was 8. A good linear relationship was observed between the peak current and the concentration of histamine in the range of 0.25–100 mg/L with the detection limit of 0.16 mg/L. The CeO2/RGO/GCE electrochemical sensor has been applied to the determination of histamine in fish samples with the spiked recoveries of 98.4% −104%. The method can be used to determine histamine content in fish products. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

水位下降对均质土坝边坡稳定性的影响

对均质土坝在水位下降时坝体的渗流和坝坡稳定性进行了分析，坝体渗流分析时采用有限单元法．坝坡稳定性分析时采用条分法．发挥有限单元法和条分法两个方法的长处，并结合运用，可供工程设计人员参考使用．     

同位素峰型计算在归属多元素团簇质谱中的应用

介绍了一种通过计算分子的同位素丰度模拟质谱峰型，根据比较质谱峰的位置和形状来帮助归属多元素团簇的飞行时间质谱的方法。这种方法不仅有助于归属完全分辨的低质量离子峰，还能从重叠的质谱峰中确定各个组份的相对含量。