Aptamer-functionalized Ti3C2-MXene Nanosheets with One-step Potentiometric Detection of Programmed Death-ligand 1

This communication describes a simple sensitive one-step potentiometric aptasensing method for quantitative detection of a referenced therapeutic biomarker (programmed death-ligand 1, PD−L1). The aptasensor is constructed by modifying PD−L1-specific aptamer on Ti₃C₂-MXene nanosheets-functionalized electrode. Introduction of PD−L1 induces the specific reaction between PD−L1 and aptamer, thereby resulting in the change of spatial structures. The surface electric potential of modified electrode is shifted upon addition of PD−L1 proteins before and after the reaction of aptamer with the analyte. Interestingly, potentiometric aptamer with Ti₃C₂-MXene nanosheets can achieve a higher sensitivity and a lower detection limit toward target PD−L1 relative to aptamer-modified electrode. Experimental results indicated that the linear range and detection limit of using Ti₃C₂-MXene nanosheets were 0.01–100 ng mL⁻¹ and 7.8 pg mL⁻¹ PD−L1, respectively. Meanwhile, the specificity, reproducibility, storing stability and accuracy of potentiometric aptasensor are acceptable for the screening of PD−L1 in human serum samples.     

SIMULTANEOUS MEASUREMENTS OF THICKNESS AND TEMPERATURE PROFILE IN A WAVY LIQUID FILM FALLING FREELY ON A HEATING WALL

A technique far measuring the thickness of liquid films was developed and successfully tested. The feasibility of this technique was demonstrated in stagnant liquid films as well as in liquid jets. A procedure for in-situ calibration of the thickness probe was developed, allowing the adaptation of the probe to measurements of wavy liquid films. The thickness probe was constructed from a platinum-rhodium wire that was stretched across the film. A constant DC current was supplied through the probe wire, and film thickness was determined from variations in the probe voltage drop resulting from the large differences in the electrical resistances of the wetted and unwetted segments of the wire. Unlike electrical admittance thickness probes, the new probe did not require dissolving an electrolyte in the liquid, making the new probe well suited to studies involving sensible heating of a film of pure dielectric liquid that is in duvet contact with a current-carrying wall. Also presented is a composite probe that facilitated simultaneous measurements of temperature profile across a wavy liquid film and film thickness. Experimental results demonstrate a strong influence of wariness on liquid temperature in a film of deionized water falling freely on the outside wall of a vertical, electrically heated tube for film Reynolds numbers smaller than 10,000.     

基于传感器控制的多级磁阻式电磁炮制作与研究

针对磁阻式电磁发射器的技术特点,设计了一种基于传感器控制的多级电磁炮射击装置,并成功试制了电磁发射装置样品,通过单级加电压和改变炮弹初始位置的方法对样品进行试射,并在此基础上加装三级加速,从而得出三级电磁炮的发射最优配置,试验证明,在280V电压下,炮弹的出口速度达到27.52m/s.     

Processing-Structure-Properties Relationships of Glycerol-Plasticized Silk Films

Silk possesses excellent mechanical properties and biocompatibility due to its unique protein sequences and hierarchical structures. Thus, it has been widely used as a biomaterial in a broad spectrum of biomedical applications. In this study, an in-depth investigation of glycerol-plasticized silk films was carried out to understand the processing-structure-properties relationships. A series of glycerol-plasticized silk films with glycerol contents in the range of 0 to 30% (w/w) were prepared. The molecular structures and organizations of silk proteins and the interactions between glycerol and proteins were studied using FTIR, XRD, and DSC. At a low glycerol content (<12%), DSC revealed that the glass transition temperature and thermally induced crystallization temperature decreased as the glycerol content increased, implying that glycerol mainly interacts with silk proteins through hydrogen bonding. As the glycerol content further increased, the chain mobility of the silk proteins was promoted, leading to the formation of β-sheet structures, water insolubility, and increased crystallinity. In addition, the stretchability and toughness of the films were significantly enhanced. The role of glycerol as a plasticizer in regulating the silk protein structures and determining the properties of the films was thoroughly discussed.     

东方超环上低杂波驱动等离子体环向旋转实验研究

旋转和旋转剪切能抑制磁流体不稳定性和增强等离子体约束.低杂波电流驱动作为未来聚变堆上可能的旋转驱动手段,探索低杂波在现有托卡马克装置上驱动等离子体旋转的驱动机制,可以为未来的聚变堆上旋转预测提供重要参考.在东方超环托卡马克装置上,早期发现了2.45 GHz的低杂波能有效驱动等离子体旋转的现象,认为是边界旋转的改变导致芯部旋转的同电流方向的增加造成的.更高频率下4.6 GHz低杂波电流驱动可以更有效地驱动同电流方向的等离子体旋转.本论文分析在欧姆背景等离子体下,不同功率的低杂波对等离子体环向旋转的影响,研究安全因子剖面变化对环向旋转的关系,利用功率调制获得了低杂波驱动旋转实验中的环向动量输运系数变化情况,发现环向动量扩散系数(χφ)、环向动量箍缩系数(Vpinch)的数值大小趋势是从芯部向靠外的区域逐渐变大.这与低杂波驱动环向旋转时,环向旋转速度由靠外的区域向芯部传递的特性吻合.     

Study on Purification and Characterization of Polyphenol Oxidase from Acetes chinensis

Acetes chinensis (belonging to the Decapoda Sergestidae genus) is widely distributed in East Asian waters and is extremely widespread and present in the shallow coastal areas of China. Polyphenol oxidase (PPO), which was extracted from Acetes chinensis, was purified in a four-step procedure involving phosphate-buffered saline treatment, ammonium sulphate precipitation, DEAE-Cellulose chromatography, and Phenyl-Sepharose HP chromatography, and then, its biochemical characterization was measured. The specific activity of the purified enzyme was increased to 643.4 U/mg, which is a 30.35 times increase in purification, and the recovery rate was 17.9%. L-dopa was used as the substrate, the enzymatic reactions catalyzed by PPO conformed to the Michaelis equation, the maximum reaction velocity was 769.23 U/mL, and the Michaelis constant K_m was 0.846 mmol/L. The optimal pH of PPO from Acetes chinensis was 7.5, and the optimal temperature was 35 °C. The metal ions experiment showed that Mn²⁺ and K⁺ could enhance the activity of PPO; that Ba²⁺ and Ca²⁺ could inhibit the activity of PPO; and that Cu²⁺ had a double effect on PPO, increasing the PPO activity at low concentrations and inhibiting the PPO activity at high concentrations. The inhibitor experiment showed that the inhibitory effects of EDTA and kojic acid were weak and that ascorbic acid and sodium pyrophosphate had good inhibitory effects. The purification and characterization of Acetes chinensis serve as guidelines for the prediction of enzyme behavior, leading to effective prevention of enzymatic browning during processing.     

固体氧化物燃料电池运行初期电化学性能演变机制

固体氧化物燃料电池(solid oxide fuel cell, SOFC)是一种清洁高效的发电装置, 其运行中的性能衰减受到众多因素的影响, 如何分辨这些因素的贡献、并在此基础上确定衰减的主导因素, 对于更有针对性地提升SOFC的运行寿命至关重要. 广泛的测试结果表明, SOFC的电化学性能在运行初期(约前100 h)会发生最为显著且复杂的变化, 但是对其演变机制还没有形成清晰的认识. 本工作基于电化学阻抗谱(electrochemical impedance spectroscopy, EIS)分析方法分别研究了工业尺寸电池(100 cm²)和纽扣电池(0.45 cm²)在运行初期的电化学性能演变规律, 得到了关于电池性能和电极微观结构演变机制的一致性规律. 电池在运行初期依次经历活化阶段和老化阶段: 活化阶段阳极孔隙率增加、气相扩散过程改善, 电池性能逐渐上升; 老化阶段阳极Ni颗粒发生烧结团聚, 有效三相界面长度显著降低, 阳极界面反应过程劣化, 电池性能逐渐下降. 各阶段的持续时间、性能变化幅度会受到电池制备工艺的影响. 本工作提出的运行初期电化学性能演变机制能够为进一步研究SOFC的长期稳定性奠定基础.     

UPLC-MS—MS法测定血液中5种吩噻嗪类药物

建立了超高效液相色谱串联质谱法测定血液中5种吩噻嗪类药物的方法。血液样品经过沉淀蛋白后,在HSSSBC18色谱柱上,经乙腈-0．1％甲酸水溶液梯度洗脱分离,用液相色谱-串联质谱仪以电喷雾电离（ESI＋）、多反应监泖l（MRM）方式进行分析。血液样本中异丙嗪、泰尔登、氯丙嗪、奋乃静、三氟拉嗪提取回收率分剐为62％-65％,71％-97％,66％-107％,72％-95％,77％-96％,检出限分别为0．02,0．01,0．01,0．01,0．01ng／mL。测定结果的相对标准偏差小于7％（n=6）。线性范围为0．05-20ng／mL,相关系数大于0．999。该方法适用于血液中吩噻嗪类药物的分析。     

Amperometric Tyrosinase Biosensor Based on Carbon Nanotube–Titania–Nafion Composite Film

A highly sensitive and stable amperometric tyrosinase biosensor has been developed based on multiwalled carbon nanotube (MWCNT) dispersed in mesoporous composite films of sol–gel‐derived titania and perfluorosulfonated ionomer (Nafion). Tyrosinase was immobilized within a thin film of MWCNT–titania–Nafion composite film coated on a glassy carbon electrode. Phenolic compounds were determined by the direct reduction of biocatalytically‐liberated quinone species at ?100 mV versus Ag/AgCl (3 M NaCl) without a mediator. The present tyrosinase biosensor showed good analytical performances in terms of response time, sensitivity, and stability compared to those obtained with other biosensors based on different sol–gel matrices. Due to the large pore size of the MWCNT–titania–Nafion composite, the present biosensor showed remarkably fast response time with less than 3 s. The present biosensor responds linearly to phenol from 1.0×10^?7 M to 5.0×10^?5 M with an excellent sensitivity of 417 mA/M and a detection limit of 9.5×10^?8 M (S/N=3). The enzyme electrode retained 89% of its initial activity after 2 weeks of storage in 50 mM phosphate buffer at pH 7.0.     

Some Conditions on Real Hypersurfaces in Quaternionic Projective Spaces in Terms of Lie Derivatives

The purpose of this paper is to give a non-existence property with the Lie derivative of the structure tensors φ _i and some characterizations of real hypersurfaces of type A ₁, A ₂ in a quaternionic projective space QP ^m in terms of the Lie derivatives of the second fundamental tensor A and the induced Riemannian metric g on the distribution D ^⊥ = Span {U ₂, U ₂, U ₃}. This revised version was published online in June 2006 with corrections to the Cover Date.