Inhibition of cold-welding and adhesive wear occurring on surface of the 6061 aluminum alloy by graphene oxide/polyethylene glycol composite water-based lubricant

In this paper, graphene oxide/polyethylene glycol (GO/PEG) composite water-based lubricant was prepared by an ultrasonic dispersion method, and characterized and analyzed by Fourier transform infrared (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The suspension performance of GO/PEG composite water-based lubricant in water was verified by static sedimentation and centrifugation, and then, the prepared GO/PEG composite water-based lubricant was added into 304 stainless steel and 6061 aluminum alloy, and the coefficient of friction (COF) curve, average COF value, average wear rate, corresponding photomicrographs of balls and disks after wear, and energy-dispersive spectrometer (EDS) elemental analysis were used to illustrate the lubrication effect and lubrication mechanism. The results show that the GO/PEG composite water-based lubricant possesses excellent suspension ability in water, and the average COF value and wear rate of GO/PEG composite water-based lubricant are reduced by 78.8% and 88.8%, respectively, compared with water lubrication. The excellent lubrication effect of GO/PEG composite water-based lubricant can effectively reduce the cold-welding and adhesive wear phenomenon, mainly because GO/PEG composite water-based lubricant first fills the uneven surface of friction mating to form a high-quality lubricating film and then because of the special space structure of GO and the low shear between GO layers and the synergistic lubrication effect of GO/PEG.     

100kV直流高温超导电缆终端应力锥设计

本文提出了一种新的单直线应力锥设计方法,根据PPLP材料的绝缘特性,结合超导电缆的本体尺寸和设计电压,给出了增饶绝缘厚度和应力锥轴向长度的设计数据,其中增饶绝缘厚度为3.5 mm,应力锥轴向长度为38.5 mm,并对单直线应力锥进行电场数值分析,结果表明,所设计的单直线应力锥满足100 kV直流高温超导电缆运行要求。     

Syntheses and Preliminary Biological Evaluations of the Dibromopyrrole-Containing Marine Natural Products Agesasine A,Agesasine B,Longamide E and Various Congeners

Total syntheses of the title marine natural products have been achieved and so confirming the structures originally assigned to them. Upon subjecting agesasine A and its corresponding ethyl ester to Mitsunobu conditions, a 1,5-cyclodehydration reaction takes place to give 2-oxazolines. In contrast, on subjecting agesasine B to the same Mitsunobu conditions, a simple dehydration reaction occurs to give the corresponding acrylate. A total synthesis of longamide E was achieved by engaging a 1,2-disubstituted pyrrole in a lactam-forming reaction and this was followed by a two-fold and fully regio-controlled bromination reaction. A distinctly different and possibly biomimetic route was used to synthesize, via the open-chain natural product nakamurine B, longamide B and its methyl ester. Preliminary biological evaluations of the title alkaloids and various analogues against a small human cancer cell line panel reveals cytotoxic properties that vary significantly with structure.     

Cyclometalated Iridium(III) Complexes as Two‐Photon Phosphorescent Probes for Specific Mitochondrial Dynamics Tracking in Living Cells

Five cyclometalated iridium(III) complexes with 2‐phenylimidazo[4,5‐f][1,10]phenanthroline derivatives ( IrL1 – IrL5 ) were synthesized and developed to image and track mitochondria in living cells under two‐photon (750 nm) excitation, with two‐photon absorption cross‐sections of 48.8–65.5 GM at 750 nm. Confocal microscopy and inductive coupled plasma‐mass spectrometry (ICP‐MS) demonstrated that these complexes selectively accumulate in mitochondria within 5 min, without needing additional reagents for membrane permeabilization, or replacement of the culture medium. In addition, photobleaching experiments and luminescence measurements confirmed the photostability of these complexes under continuous laser irradiation and physiological pH resistance. Moreover, results using 3D multicellular spheroids demonstrate the proficiency of these two‐photon luminescent complexes in deep penetration imaging. Two‐photon excitation using such novel complexes of iridium(III) for exclusive visualization of mitochondria in living cells may substantially enhance practical applications of bioimaging and tracking.     

盐酸四环素在Nafion膜上的吸附动力学及其介导的金微纳米晶体的生长

实验发现,盐酸四环素能够很好吸附到Nafion膜上,动力学研究表明其吸附是与浓度相关并由扩散控制的一级动力学过程,扩散系数为8.5×10-9 cm2 s-1,遵循BET吸附等温线,表明其多层吸附特性.研究表明,当吸附了盐酸四环素的Nafion膜浸入合适浓度的氯金酸溶液时,盐酸四环素能够介导金微纳米晶体在Nafion膜上的生长,且通过简单改变氯金酸溶液的浓度,可以调控金微纳米晶体的形态.这一实验结果为金属微纳米材料Nafion聚合物复合膜的制备提供了新思路,这种金微纳米材料Nafion聚合物复合膜在化学生物传感设计和材料科学领域具有潜在的应用价值.     

优化端点条件的平面二次均匀B样条插值曲线

在利用反求法构造B样条插值曲线时，往往需要选取端点条件。 因此，可对端点条件进行优化选取，使得构造的B样条插值曲线满足特定要求。提出了一种利用曲线内能极小选取平面二次均匀B样条插值曲线端点条件的算法。首先给出了二次均匀B样条插值曲线分控制顶点与首个控制顶点（即端点条件）的递推关系式；然后给出了利用曲线内能极小优化选取首个控制顶点的算法，证明了利用该算法构造的C¹连续二次均匀B样条插值曲线为保形插值，并通过数值算例证明了算法的有效性；最后，为便于实际应用，基于MATLAB平台设计了算法所对应的图形用户界面，用户通过简单的操作即可获得光顺的C¹连续二次均匀B样条保形插值曲线。     

氨基三唑分子印迹聚合物的制备及性能表征

采用分子印迹技术,以氨基三唑(AMI)为模板分子,异丁醇为溶剂,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酯(EDMA)为交联剂,合成了氨基三唑分子印迹聚合物(AMI-MIP)。采用静态平衡结合实验和选择性实验评价了AMI-MIP对底物分子的结合特性及分子识别性能,并进行了吸附动力学研究。结果表明,AMI-MIP对AMI存在不同亲和力的两类结合位点,且对AMI具有很高的选择吸附特性和良好的分子识别性能,AMI-MIP对AMI的吸附行为可用准二级吸附动力学方程加以描述。     

材料变形及损伤演化的微观物理动力机理

利用微观物理动力学对材料变形及损伤的演化进行了研究。探讨现有的简单应力状态及复杂应力状态的模型之间的内在联系，研究了损伤对材料变形及损伤演化的影响，得到了在考虑损伤时材料的变形及损伤的近似演化方程，该文研究表明微观物理动力学对描述材料的变形及损伤具有广泛可能性。     

Poly(2‐Oxazoline)‐Based Functional Peptide Mimics: Eradicating MRSA Infections and Persisters while Alleviating Antimicrobial Resistance

Peptides have important biological functions. However, their susceptibility to proteolysis limits their applications. We demonstrated here for the first time, that poly(2‐oxazoline) (POX) can work as a functional mimic of peptides. POX‐based glycine pseudopeptides, a host defense peptide mimic, had potent activities against methicillin‐resistant S. aureus, which causes formidable infections. The POX mimic showed potent activity against persisters that are highly resistant to antibiotics. S. aureus did not develop resistance to POX owning to the reactive oxygen species related antimicrobial mechanism. POX‐treated S. aureus is sensitive to common antibiotics, demonstrating no observable antimicrobial pressure or cross‐resistance in using antimicrobial POX. This study highlights POX as a new type of functional mimic of peptides and opens new avenues in designing and exploring peptide mimetics for biological functions and applications.