Injectable Bone Cement Reinforced with Gold Nanodots Decorated rGO-Hydroxyapatite Nanocomposites,Augment Bone Regeneration

Interest in the development of new generation injectable bone cements having appropriate mechanical properties, biodegradability, and bioactivity has been rekindled with the advent of nanoscience. Injectable bone cements made with calcium sulfate (CS) are of significant interest, owing to its compatibility and optimal self-setting property. Its rapid resorption rate, lack of bioactivity, and poor mechanical strength serve as a deterrent for its wide application. Herein, a significantly improved CS-based injectable bone cement (modified calcium sulfate termed as CS_mod), reinforced with various concentrations (0–15%) of a conductive nanocomposite containing gold nanodots and nanohydroxyapatite decorated reduced graphene oxide (rGO) sheets (AuHp@rGO), and functionalized with vancomycin, is presented. The piezo-responsive cement exhibits favorable injectability and setting times, along with improved mechanical properties. The antimicrobial, osteoinductive, and osteoconductive properties of the CS_mod cement are confirmed using appropriate in vitro studies. There is an upregulation of the paracrine signaling mediated crosstalk between mesenchymal stem cells and human umbilical vein endothelial cells seeded on these cements. The ability of CS_mod to induce endothelial cell recruitment and augment bone regeneration is evidenced in relevant rat models. The results imply that the multipronged activity exhibited by the novel-CS_mod cement would be beneficial for bone repair.     

Engineering Catalytically Active Sites by Sculpting Artificial Edges on MoS2 Basal Plane for Dinitrogen Reduction at a Low Overpotential

Engineering catalytically active sites have been a challenge so far and often relies on optimization of synthesis routes, which can at most provide quantitative enhancement of active facets, however, cannot provide control over choosing orientation, geometry and spatial distribution of the active sites. Artificially sculpting catalytically active sites via laser-etching technique can provide a new prospect in this field and offer a new species of nanocatalyst for achieving superior selectivity and attaining maximum yield via absolute control over defining their location and geometry of every active site at a nanoscale precision. In this work, a controlled protocol of artificial surface engineering is shown by focused laser irradiation on pristine MoS₂ flakes, which are confirmed as catalytic sites by electrodeposition of AuNPs. The preferential Au deposited catalytic sites are found to be electrochemically active for nitrogen adsorption and its subsequent reduction due to the S-vacancies rather than Mo-vacancy, as advocated by DFT analysis. The catalytic performance of Au-NR/MoS₂ shows a high yield rate of ammonia (11.43 × 10⁻⁸ mol s⁻¹ cm⁻²) at a potential as low as −0.1 V versus RHE and a notable Faradaic efficiency of 13.79% during the electrochemical nitrogen reduction in 0.1 m HCl.     

含砷金矿石工艺矿物学特征及其应用

通过典型实例分析,对含砷金矿石的工艺矿物学特征及应用进行了探讨,对金矿石除砷具有重要意义．     

简单0-1规划问题的动态DNA折纸计算模型

DNA折纸是一种全新的DNA自组装方法。将一个由DNA折纸卡槽、双态DNA机器、DNA行走机器人组装而成的动态折纸应用于求解0-1规划问题。其中DNA折纸卡槽由1条M13脚手架链和202条钉书钉链折叠而成。双态DNA机器分为不修饰和修饰金纳米颗粒两种情况,对应于0-1规划问题约束变量的取值为0或者1。DNA折纸卡槽和DNA双态机器组装成折纸基底。DNA行走机器人是7条单链折叠成的带有粘性末端的DNA折纸。在链的驱动下,DNA行走机器人在折纸基底上顺时针旋转行走,每步旋转120°。DNA行走机器人每走两步,与折纸基底上的DNA双态机器进行链置换,接收修饰的金纳米颗粒。当整个动态行走过程结束,根据透射电镜下DNA行走机器人接收的金纳米颗粒的大小和个数来判断约束变量的取值是否为可行解。该计算模型采用模块化结构,DNA折纸卡槽、双态DNA机器、DNA行走机器人等折纸均单独设计,且采用透射电镜读解,因而提高了模型实现的可行性。     

Synthesis of Octapod Cu-Au Bimetallic Nanocrystal with Concave Structure through Galvanic Replacement Reaction

We synthesized octapod Cu-Au bimetallic alloy with a concave structure by employing a replacement reaction between AuPPh₃Cl and Cu nanocubes. Using the Cu nanocube as sacrificial templates, we have successfully generated high-active sites on alloy nanocrystals by carefully tuning the replacement reaction and growth. The key is to afford the proper concentration of AuPPh₃Cl-TOP to the reaction solution. When the Au precursor with high concentration is injected into the galvanic replacement reaction, the growth dominated the process and hollowed octapod Cu-Au alloy was obtained. In contrast, when the concentration of the Au precursor is low, the replacement reaction can only take place at the nanocrystals, leading to generate Cu-Au nanocages. This work provides an effective strategy for the preparation of hollow bimetallic nanocrystals with high-active sites.     

修饰不同金纳米颗粒的极大角倾斜光纤光栅折射率传感特性研究

研究了分别使用大尺寸金纳米壳与星型金纳米颗粒修饰极大角倾斜光纤光栅(ExTFG)的局域表面等离子体共振(LSPR)传感器,实验对比了这两种ExTFG-LSPR传感器的折射率传感特性。实验结果表明:修饰星型金纳米颗粒的ExTFG传感器,其TM、TE模的基于波长变化的折射率灵敏度分别提升约15.52和12.8nm/RIU,但共振吸收效应不明显;而修饰大尺寸金纳米壳的ExTFG传感器,在大尺寸金纳米壳的LSPR作用下,其TM、TE模的基于波长变化的折射率灵敏度分别提升约31.1和26.99nm/RIU,同时,TM与TE模在C-L波段表现出强烈的共振吸收,基于归一化强度变化的折射率灵敏度分别约为185.18%/RIU和251.83%/RIU。     

Catalytic properties of oxide nanoparticles applied in gas sensors

A series of gas sensing layers based on indium oxide doped with gold were prepared by using the aerosol technology for deposition as the active contact layer in a metal oxide semiconductor capacitive device. The interaction between the measured species and the insulator surface was quantified as the voltage changes at a constant capacitance of the device. The sensor properties were investigated in the presence of H₂, CO, NH₃, NO, NO₂ and C₃H₆ at temperatures between 100–400 °C. Significant differences in the morphology of the layer and its sensitivity were noted for different preparation methods and different gas environments.     

An overview of gold-catalysed oxidation processes

Gold and gold/platinum group metals (Au/PGM) catalysts are active under mild conditions or even at ambient temperature or less and this makes them unique. They will therefore be effective in reducing running costs of chemical plants and increasing the selectivity of the reactions involved where applicable. In pollution control applications such as air cleaning, low light-off autocatalysts, and purification of hydrogen streams used for fuel cells they have the characteristics to become the catalysts of choice, especially now that their durability and resistance to poisons is being shown to be better than was anticipated. The mechanisms of these gold catalysed reactions are still uncertain but both oxidised and metallic gold are probably involved, and the details depend on types of reaction and the conditions used.     

Towards Recyclable Nanoporous Polymer Membranes for the Synthesis of One-dimensional Nanoscale Gold Colloids

Proof-of-concept studies towards recyclable nanoporous track-etched polymer membranes for template-synthesis of one-dimensional colloidal gold rods indicate that surfactant-capped gold nanorods can be synthesised within and isolated from polyethylene terephthalate (Lavsan) membranes using organic solvents with or without sonication. Thereafter, the same Lavsan membrance can be re-used for at least one to two additional synthetic cycles. An erratum to this article can be found at     

Interaction of Au with titania: the role of reduced Ti

The interaction of Au with oxide supports has been found to play a vital role in determining the unique properties of Au catalysts. In this study, the binding of Au with titania was investigated using scanning tunneling microscopy (STM) and ultra-violet photoemission spectroscopy (UPS). Two support systems, rutile TiO₂(110) and an ordered TiO _x /Mo(112) thin film were used. On a highly defective TiO₂(110) surface, Au particles were found to bind first on the oxygen vacancy sites. Complete wetting of the oxide by Au was found on an ordered and reduced Ti³⁺O _x /Mo(112) film to form two ordered structures, a (1 × 1)-monolayer and a (1 × 3)-Au/TiO _x /Mo(112) bi-layer. Detailed STM images confirm the proposed structural models. Reduced titania was found to enhance the binding of Au with Ti sites and promote electron donation from Ti^δ+ to Au, leading to electron-rich Au and to enhanced CO bonding.