Response of saturated porous media subjected to local thermal loading on the surface of semi-infinite space

Heat source function method is adopted in the present paper to derive elementary solutions of coupled thermo-hydro-mechanical consolidation for saturated porous media under conjunct actions of instantaneous point heat source, instantaneous point fluid source and constant volume force. By using the so-called fictitious heat source method and images method, the solutions of a semi-infinite saturated porous medium subjected to a local heat source with time-varied intensity on its free surface are developed from elementary solutions. The numerical integral methods for calculating the unsteady temperature, pore pressure and displacement fields are given. The thermomechanical response are analyzed for the case of a circular planar heat source. Besides, the thermal consolidation characteristics of a saturated porous medium subjected to a harmonic thermal loading are also given, and the fluctuation processes of the field variables located below the center of heat source are analyzed. The project supported by the National Natural Science Foundation of China (50578008) The English text was polished byYunming Chen.     

气相色谱矩形离子阱质谱联用仪的设计与性能

气相色谱离子阱质谱联用仪(GC-ITMS)广泛地应用于药物分析、环境分析、农药检测和食品分析、有机化学品分析、毒品分析以及医学和生物分析等领域。离子阱质谱作为色谱的检测器,决定了色质联用仪的分析性能,包括检出限、分辨率。离子阱质量分析器从传统的双曲型3D离子阱发展到2D线性离子阱,质量歧视效应得到了极大的改善,灵敏度得到了提高。矩形离子阱作为线性离子阱,结构简单,加工和装配容易,因此应用到GCMS系统中将具有非常大的优势。介绍了矩形离子阱质谱仪的设计方案、仪器整机的性能测试、质量分辨和质量歧视效应分析,与Agilent6890组成GCMS联用仪,对实际样品进行了分析。     

A Fault Detection Method for Electrohydraulic Switch Machine Based on Oil-Pressure-Signal-Sectionalized Feature Extraction

A turnout switch machine is key equipment in a railway, and its fault condition has an enormous impact on the safety of train operation. Electrohydraulic switch machines are increasingly used in high-speed railways, and how to extract effective fault features from their working condition monitoring signal is a difficult problem. This paper focuses on the sectionalized feature extraction method of the oil pressure signal of the electrohydraulic switch machine and realizes the fault detection of the switch machine based on this method. First, the oil pressure signal is divided into three stages according to the working principle and action process of the switch machine, and multiple features of each stage are extracted. Then the max-relevance and min-redundancy (mRMR) algorithm is applied to select the effective features. Finally, the mini batch k-means method is used to achieve unsupervised fault diagnosis. Through experimental verification, this method can not only derive the best sectionalization mode and feature types of the oil pressure signal, but also achieve the fault diagnosis and the prediction of the status of the electrohydraulic switch machine.     

结合表面引发的原子转移自由基聚合和气/固反应制备CdS纳米微粒/聚苯乙烯核壳微球

结合表面引发的原子转移自由基聚合和气/固反应制备CdS纳米微粒/聚苯乙烯核壳微球. 以表面富含环氧基团的聚苯乙烯微球为基底, 利用开环反应在水相中一步接枝表面引发剂, 然后在聚苯乙烯微球表面引发甲基丙烯酸镉的原子转移自由基聚合, 最后通入H2S气体原位生成CdS纳米微粒. 生成的CdS纳米微粒复合的核壳微球呈草莓状形貌, 且具有良好的光学性能.     

Structural and Functional Analysis of the Pyridoxal Phosphate Homeostasis Protein YggS from Fusobacterium nucleatum

Pyridoxal 5′-phosphate (PLP) is the active form of vitamin B6, but it is highly reactive and poisonous in its free form. YggS is a PLP-binding protein found in bacteria and humans that mediates PLP homeostasis by delivering PLP to target enzymes or by performing a protective function. Several biochemical and structural studies of YggS have been reported, but the mechanism by which YggS recognizes PLP has not been fully elucidated. Here, we report a functional and structural analysis of YggS from Fusobacterium nucleatum (FnYggS). The PLP molecule could bind to native FnYggS, but no PLP binding was observed for selenomethionine (SeMet)-derivatized FnYggS. The crystal structure of FnYggS showed a type III TIM barrel fold, exhibiting structural homology with several other PLP-dependent enzymes. Although FnYggS exhibited low (<35%) amino acid sequence similarity with previously studied YggS proteins, its overall structure and PLP-binding site were highly conserved. In the PLP-binding site of FnYggS, the sulfate ion was coordinated by the conserved residues Ser201, Gly218, and Thr219, which were positioned to provide the binding moiety for the phosphate group of PLP. The mutagenesis study showed that the conserved Ser201 residue in FnYggS was the key residue for PLP binding. These results will expand the knowledge of the molecular properties and function of the YggS family.     

Effect of Different Processing Methods on the Chemical Constituents of Scrophulariae Radix as Revealed by 2D NMR-Based Metabolomics

Scrophulariae Radix (SR) is one of the oldest and most frequently used Chinese herbs for oriental medicine in China. Before clinical use, the SR should be processed using different methods after harvest, such as steaming, “sweating”, and traditional fire-drying. In order to investigate the difference in chemical constituents using different processing methods, the two-dimensional (2D) ¹H-¹³C heteronuclear single quantum correlation (¹H-¹³C HSQC)-based metabolomics approach was applied to extensively characterize the difference in the chemical components in the extracts of SR processed using different processing methods. In total, 20 compounds were identified as potential chemical markers that changed significantly with different steaming durations. Seven compounds can be used as potential chemical markers to differentiate processing by sweating, hot-air drying, and steaming for 4 h. These findings could elucidate the change of chemical constituents of the processed SR and provide a guide for the processing. In addition, our protocol may represent a general approach to characterizing chemical compounds of traditional Chinese medicine (TCM) and therefore might be considered as a promising approach to exploring the scientific basis of traditional processing of TCM.     

荧光纳米晶制备及其与聚合物的复合组装

纳米尺寸无机晶体(纳米晶)具有特殊的光、电和磁等性能, 但这类材料通常以胶体溶液或固体粉末的状态存在, 稳定性和分散性较差. 实现这类材料的应用, 需要将其与一些惰性介质复合, 从而提高稳定性和加工性. 聚合物材料作为一种有机惰性介质, 具有良好的材料兼容性和可加工性, 是稳定纳米晶材料的首选介质. 此外, 很多聚合物材料本身也具备特殊的性能, 可以对纳米晶性能进行有益的补充和调节. 因此, 功能纳米晶材料与聚合物复合, 将成为开启材料性能宝库的钥匙. 我们研究组结合自己的相关研究, 系统总结了荧光纳米晶材料与聚合物的复合组装方法, 着重阐述不同方法的优势及意义, 希望对从事这一前沿领域研究的人们有所启发.     

C波段加速器初步热测实验

为了开展加速器小型化技术研究,进行了C波段2 MeV驻波加速器研制工作。目前,该加速器研制取得了显著进展,完成了全密封加速管的焊接,建立了加速器热测实验平台。在重复频率50 Hz情况下,进行了初步热测出束实验,利用电离室剂量仪测试了加速器靶前1 m处的X射线剂量率,并利用钢吸收法测试了电子束的能量。初步实验结果表明:电子束能量约2.5 MeV,剂量率超过330 mGy/(minm)。     

一维线性非共轭石墨烯基(CH2)n分子链的电子输运

一维非共轭烷烃链虽不具富电子或少电子特征,但常存在于单分子器件或多肽、蛋白质等生物分子中,对电子传输产生重要影响.为理解这类物质的电子输运特征,本研究设计了一维线性非共轭(CH2)n分子结模型,并利用密度泛函理论结合非平衡态格林函数的方法,对(CH2)n(n=1—12)线性分子链与两个石墨烯电极耦合而成的分子结进行了第...     

A Calixarene Assembly Strategy of Combined Anti-Neuroinflammation and Drug Delivery Functions for Traumatic Brain Injury Therapy

Excessive inflammatory reaction aggravates brain injury and hinders the recovery of neural function in nervous system diseases. Microglia, as the major players of neuroinflammation, control the progress of the disease. There is an urgent need for effective non-invasive therapy to treat neuroinflammation mediated by microglia. However, the lack of specificity of anti-inflammatory agents and insufficient drug dose penetrating into the brain lesion area are the main problems. Here, we evaluated a series of calixarenes and found that among them the self-assembling architecture of amphiphilic sulfonatocalix[8]arene (SC8A12C) had the most potent ability to suppress neuroinflammation in vitro and in vivo. Moreover, SC8A12C assemblies were internalized into microglia through macropinocytosis. In addition, after applying the SC8A12C assemblies to the exposed brain tissue, we observed that SC8A12C assemblies penetrated into the brain parenchyma and eliminated the inflammatory factor storm, thereby restoring neurobiological functions in a mouse model of traumatic brain injury.