铜树枝晶的水热合成以及结构表征和抗菌性能评价(英文)

在乙醇胺-水混合溶液中采用水热处理硫酸铜的方法制备了多结构的铜树枝晶;采用X射线粉末衍射仪、扫描电子显微镜、透射电子显微镜分析了所得样品的结构和形貌;采用牛津杯法评价了其对金黄葡萄球菌、枯草芽孢杆菌、大肠杆菌和绿脓杆菌的抗菌性能.结果表明,铜树枝晶由一个长的一级中心主干和许多高度对称分布在主干两侧的二级分支结构构成,且形貌均匀;反应温度、反应时间以及溶剂组成对铜树枝晶的形貌有很大影响.与此同时,铜树枝晶表现出选择性的抗菌行为,对金黄葡萄球菌、枯草芽孢杆菌和绿脓杆菌更有效.     

Synthesis and antibacterial activity of Ag/CeO<Subscript>2</Subscript> hybrid architectures

Flower-like ceria (CeO₂) architectures consisting of well aligned nanosheets were first synthesized by a glycol solvothermal method. The size of CeO₂ architectures is about 5?μm in width and 10?μm in length, with the nanosheets thickness below 100?nm. Subsequently, the adsorbed Ag ions on the surface of CeO₂ were in situ reduced to form Ag nanoparticles (NPs), leading to the fabrication of Ag/CeO₂ hybrid architectures (HAs). The formed Ag NPs with sizes of 20–40?nm were uniformly loaded on the surface of the CeO₂ sheets. The antibacterial properties of Ag/CeO₂ HAs against Gram-negative E. coli and Gram-positive S. aureus were evaluated by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and a filter paper inhibition zone method. The results demonstrated that Ag/CeO₂ HAs displayed excellent antibacterial activity toward S. aureus and E. coli, which were attributed to the synergistic antibacterial effect between Ag NPs and CeO₂ in HAs_. Here, CeO₂ nanoflowers as a new substrate could restrict Ag NPs aggregations and improve their antibacterial activities. Therefore, the resulted Ag/CeO₂ HAs would be considered as a promising antibacterial agent.

Open image in new window

     

Controlling synthesis of BiIn dendritic nanocrystals by solution dispersion

In this study, we report a novel and simple solution-phase route for one-dimensional metal nanocrystals. BiIn nanocrystals were prepared by directly dispersing melting BiIn alloy at an appropriate solvent. The as-obtained BiIn nanocrystals with a dendritic shape possess a good crystalline phase. The morphology of the nanocrystals can be greatly modified by changing the reaction parameters. This strong UV emission might arise from the quantum-confined In2O3 particles.     

Electrodeposition and characterization of assembly of Sn on Cu nanorods for Li-ion microbattery application

Assembly of Sn on Cu Nanorods as anode for Li-ion microbatteries was prepared by a two-step electrodeposition design. Firstly, Cu nanorods arrays were grown on copper substrate by anodic aluminum oxide template-assisted growth method. Then, Sn was deposited onto Cu nanorods arrays by galvanostatic deposition. X-ray diffraction and scanning electron microscopy measurements reveal that Cu nanorod arrays are covered with Sn. Electrochemical performances of prepared electrodes were evaluated by charge/discharge cycle measurement. The assembly of Sn on Cu nanorods electrode exhibited highly reversible specific capacity and superior capacity retention resulting from the three-dimensionally nano-architectured design, which exhibits a large surface area, shortened Li-ion diffusion distance, Cu–Sn alloying, and can accommodate the volume expansion of Sn during cycling. Deposition time is an important parameter for fabricating the assembly of Sn on Cu nanorods electrode with suitable structure and morphology.

     

Photoelectrochemical determination of Hg(II) via dual signal amplification involving SPR enhancement and a folding-based DNA probe

The authors describe a highly sensitive and selective photoelectrochemical (PEC) assay for mercury(II) ions. It is based on a dual signal amplification strategy. The first enhancement results from the surface plasmon resonance (SPR) of Au@Ag nanoparticles (NPs) absorbed on MoS₂ nanosheets. Here, the injection of hot electrons of Au@Ag NPs into MoS₂ nanosheets produces a strong photocurrent, while background signals are strongly reduced. The second enhancement results from the use of a thymine rich ct-DNA aptamer attached to the Au@Ag-MoS₂ nanohybrid. The DNA specifically binds Hg(II) ions to form thymine-Hg(II)-thymine (T-Hg-T) complexes. This leads to the formation of a hairpin-shaped dsDNA structure. The use of a CdSe quantum dot label at the terminal end of the ct-DNA further facilitates electron–hole separation. The photocurrent of the detector is measured as a function of Hg(II) concentration at a bias voltage of 0.1 V and under irradiation of 430 nm light. Due to the two-fold amplification strategy presented here, the linear range extends from 10 pmol·L^?1 to 100 nmol·L^?1, with a detection limit of 5 pmol·L^?1 (at S/N?=?3).

Open image in new window

Graphical Abstract The injection of hot electrons of Au@Ag into MoS₂ produces a strong photocurrent, and the formation of thymine-Hg(II)-thymine further facilitates electron–hole separation by CdSe. This dual signal amplification strategy is used to detect Hg(II) ions via a photoelectrochemical assay.

     

Fabrication and Tribological Properties of Pb Nanoparticles

In this paper, we describe a surfactant-assisted solution dispersion method to obtain metal nanoparticles, which involves dispersing and stabilizing metal droplets in an appropriate solvent. This method has been successfully used to prepare Pb nanoparticles from bulk Pb. The X-ray powder diffraction and transmission electron microscopy investigations show the formation of Pb nanoparticles possessing the same crystal structure as bulk metal and an average particle diameter of 40 nm. Thermal analysis indicates that Pb nanoparticles have organic shell, which is in agreement with the excellent oil-solubility. In addition, the tribological properties of Pb nanoparticles as additive in oil are discussed.     

聚苯胺的合成及其摩擦学行为的研究

选择合适的ＳＤＢＳ／ 苯胺／ 水三组分Ｏ／Ｗ 微乳液与苯胺单体共存的两相体系,以单体相为单体源,在Ｏ／Ｗ 三组分微乳液中进行了苯胺聚合,成功地制备出了能够稳定分散于石腊油的聚苯胺微粒。并在四球试验机上研究合成条件、负荷、浓度对其摩擦学行为的影响。结果表明：聚苯胺有一定的减摩抗磨效果     

Xylene as a New Polymerizable Additive for Overcharge Protection of Lithium Ion Batteries

The electrochemical properties and overcharge protection mechanism of xylene as a new polymerizable electrolyte additive for overcharge protection of lithium ion batteries were studied by cyclic voltammetry tests, charge- discharge performance and battery power capacity measurements. It was found that when the battery was overcharged, xylene could electrochemically polymerize at the overcharge potential of 4.3—4.7 V (vs. Li/Li＋) to form a thin polymer film on the surface of the cathode, thus preventing voltage runaway. On the other hand, the use of xylene as an overcharge protection electrolyte additive did not influence the normal performance of lithium ion batteries.     

羟基磷灰石微球的制备、应用和功能化

羟基磷灰石(HA)是人体和动物骨骼的主要无机矿物成分。近年来,因HA具有特殊的表面特性和理化性能,良好的生物相容性、生物活性和骨传导作用,制备各种形态的HA材料成为从事生物、医学和材料的科研人员的研究重点。本文首先介绍了HA微球的制备方法,重点讨论了以聚合物为软模板以及用各种球形材料作为硬模板合成HA微球的制备方法,列出了不同方法制备HA微球的直径、孔径、比表面等各种性能参数。由于HA微球具有比表面积大、流动性好、质量轻、强度大,注射性能好,团聚能力低等HA块材不具有的特点,其在载体、骨修复材料、环境保护和色谱分离上有广泛的应用。针对HA微球在应用过程中遇到的问题,可采用表面改性或包覆、掺杂和将HA分散在其他基体中等措施对HA微球进行功能化修饰。HA 微球在控释载体、蛋白质分离以及细胞支架等方面具有极大的应用前景。     

Boundary layer viscosity of CNT-doped liquid crystals: effects of phase behavior

Carbon nanotube (CNT)-doped liquid crystals (LCs) have attracted intensive research studies as prospective materials in optic display devices, microfluidic sensors, and lubricants due to their unique molecular structures and properties. In this paper, the interaction between the doped CNTs and the hosting 4-cyano-4 $^{\prime }$ -pentylbiphenyl (5CB) molecules (in both nematic and isotropic phases) was investigated and we focused on the boundary layer rheological properties of the CNT-doped 5CB under external electric field. The experiments were performed by using a quartz crystal microbalance (for boundary layer viscosity investigation) and a rheometer (for bulk viscosity measurement). The results indicate that the bulk viscosity of the CNT-doped 5CB presents an obvious electroviscous effect in its nematic phase while no electroviscous effect in its isotropic phase. Additionally, we found that the boundary layer viscosity of the CNT-doped 5CB demonstrated significant electroviscous effects both in its nematic phase and isotropic phase. The enhanced electroviscous effects on the boundary layer viscosity of CNT-doped 5CB can be attributed to the highly ordered structures of LC molecules and CNTs on the substrate under external electric field. The unique properties of the boundary layer rheology of CNT-doped 5CB LC were further discussed in view of the ordering of LC molecules induced by the electric field, the polarity of CNTs, and the aligning interaction between CNTs and LC molecules.