A numerical study on subcooled flow boiling heat transfer in tubes with various helical angles at underwater vehicles conditions

Journal of Thermal Analysis and Calorimetry - As a direct source of power, the water vapor with high temperature and high pressure affects the thermal efficiency of an underwater vehicle power...     

Molecular dynamics simulation of the key characteristics of the supercritical CO<Subscript>2</Subscript>–pentaerythritol tetraacetate system

Supercritical CO₂ is widely used in many fields of industry. Investigation of statistical mechanics of CO₂ fluid under quasi critical and supercritical state has great significance. Equilibrium molecular dynamics (EMD) simulations are carried out to investigate the statistical mechanics and macroscopic performance of CO₂ fluid under the quasi critical and supercritical state. The results show that the bond length and bond angle distributions for supercritical CO₂ are Gaussian distribution basically. The dimers’ proportion of supercritical CO₂ system changes with pressure increasing. T-type dimer has high share within the system when pressure is higher than 9MPa. It can be inferred that T-type dimer leads to CO₂ physical properties changing tempestuously under supercritical state. The effect that lubricating oil has on microstructure and heat transfer of supercritical CO₂ is also investigated in the present work. The results show the lubricating oil produces significant effect on the dimers’ structure under low pressure.     

从氨的合成认识氮分子化学键的稳定性和活化

先从氮分子的化学键讨论其稳定性,再从最早工业化的合成氨出发,讨论氮分子化学键活化的相关研究,意欲探索一种元素化学新的教学方法。目的在于引导学生灵活学习并运用知识去认识自然世界,提高分析问题和解决问题的能力。     

A bifunctional electrochemical aptasensor based on AuNPs-coated ERGO nanosheets for sensitive detection of adenosine and thrombin

A simple and sensitive bifunctional electrochemical aptasensor for detection of adenosine and thrombin has been developed using gold nanoparticles–electrochemically reduced graphene oxide (AuNPs-ERGO) composite film-modified electrode. Firstly, the reduced graphene oxide film and AuNPs were sequentially immobilized on glassy carbon electrode (GCE) surface. Secondly, thrombin aptamer was immobilized on the modified electrode. Finally, adenosine aptamer was hybridized with it to serve as a recognition element and methylene blue (MB) as electrochemical signal indicator. In the presence of adenosine or thrombin, the sensor recognized it and a conformational change was induced in aptamer, resulting in decrease of the peak current of MB. The linear relation between concentration of adenosine or thrombin and peak current of MB allowed quantification of them. Thanks to the special electronic characteristic of AuNPs-ERGO composite film, sensitivity of sensor was greatly improved. Under optimal conditions, the proposed aptasensor presented an excellent performance in a linear range of 25 nM to 750 nM for adenosine and 0.5 nM to 10 nM for thrombin. Detection limits were estimated to be 8.3 nM for adenosine and 0.17 nM for thrombin, respectively. Moreover, dual-analyte detection of adenosine and thrombin was achieved without potentially increasing the complexity and cost of the assay.

     

Research progress of the retrospective detection of organophosphorus nerve agent exposure using point-of-care testing techniqueEI北大核心CSCD

有机磷神经性毒剂(OPNA)是一类速杀性化学战剂,人员中毒后通过溯源检测来确定OPNA种类和剂量对于毒剂使用指证和人员救治非常重要。当前大部分溯源检测方法灵敏度高、特异性好,但因依赖大型设备限于实验室,不便于现场检测。随着现场快速检测(POCT)技术的发展和新识别分子的开发,大量OPNA中毒溯源现场检测技术被建立和应用。本文主要基于胆碱酯酶活性抑制、特异性识别和直接生化反应原理从3方面分析总结了OPNA中毒溯源POCT技术的研究进展和应用,展望了其未来发展趋势。     

相对AR-对应, 余$t$-结构和半倾斜对

作为倾斜对的推广,本文提出了半倾斜对的概念.作者们将Bazzoni关于倾斜模的刻画推广至半倾斜对,证明了半倾斜对的等价类和满足一定条件的某个子范畴之间存在一个1-1对应.进一步给出了半倾斜对的等价类和上有界的余$t$-结构两者之间存在一个双射.     

喷流型发生器、氢化物-原子吸收光谱法测定岩石、矿物中的铅

本文采用喷流型连续氢化物发生器,氢化物-火焰原子吸收光谱法对岩石、矿物中微量铅的测定条件进行了研究。用铁氰化钾作为铅的氧化剂,草酸为干扰抑制剂,于217.0nm波长,测得铅的特征浓度为0.012μg/ml(1％吸收)。相对标准偏差(对0.6μg/ml Pb)为0.97％。     

Modulating the stacking modes of nanosized metal–organic frameworks by morphology engineering for isomer separation

Modulating different stacking modes of nanoscale metal–organic frameworks (MOFs) introduces different properties and functionalities but remains a great challenge. Here, we describe a morphology engineering method to modulate the stacking modes of nanoscale NU-901. The nanoscale NU-901 is stacked through solvent removal after one-pot solvothermal synthesis, in which different morphologies from nanosheets (NS) to interpenetrated nanosheets (I-NS) and nanoparticles (NP) were obtained successfully. The stacked NU-901-NS, NU-901-I-NS, and NU-901-NP exhibited relatively aligned stacking, random stacking, and close packing, respectively. The three stacked nanoscale NU-901 exhibited different separation abilities and all showed better performance than bulk phase NU-901. Our work provides a new morphology engineering route for the modulation of the stacking modes of nano-sized MOFs and improves the separation abilities of MOFs.

A morphology engineering method was utilized to modulate the stacking modes of three nano-NU-901 materials, leading to different separation abilities for isomers.     

求解一类广义Nash均衡问题

Generalized Nash equilibrium problem (GNEP) is an important model that has many applications in practice. However, a GNEP usually has multiple or even infinitely many Nash equilibrium points and it is not easy to choose a favorable solution from those equilibria. This paper considers a class of GNEP with some kind of separability. We first extend the so-called normalized equilibrium concept to the stationarity sense and then, we propose an approach to solve the normalized stationary points by reformulating the GNEP as a single optimization problem. We further demonstrate the proposed approach on a GNEP model in similar product markets.