Green synthesis of zinc oxide nanoparticles using tomato (Lycopersicon esculentum) extract and its photovoltaic application

With an increasing awareness of green and clean energy, zinc oxide-based solar cells were found to be suitable candidates for cost-effective and environmentally friendly energy conversion devices. In this paper, we have reported the green synthesis of zinc oxide nanoparticles (ZnONPs) by thermal method and under microwave irradiation using the aqueous extract of tomatoes as non-toxic and ecofriendly reducing material. The synthesised ZnONPs were characterised by UV–visible spectroscopy (UV–vis), infra-red spectroscopy, particle size analyser, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction study (XRD). A series of ZnO nanocomposites with titanium dioxide nanoparticles (TiO₂) and graphene oxide (GO) were prepared for photovoltaic application. Structural and morphological studies of these nanocomposites were carried out using UV–vis, SEM, XRD and AFM. The current–voltage measurements of the nanocomposites demonstrated enhanced power conversion efficiency of 6.18% in case of ZnO/GO/ TiO₂ nanocomposite.     

原子力显微镜表征纤维增强聚合物复合材料的界面相概述

纤维增强聚合物复合材料(FRPC)的界面相是一个尺度只有几十纳米到几微米之间的微小区域,是复合材料中应力传递的枢纽,对复合材料的整体性能起着至关重要的作用。因此,急需寻求一种高分辨率的纳米探测技术来表征该区域并研究其性能,这对复合材料的结构设计有着重要的科学意义和指导作用。文章概述了几种原子力显微镜(AFM)常见应用模式,并且阐述了采用AFM表征FRPC界面相的研究现状,总结了目前存在的问题并提出未来的研究方向。     

Nanocrystalline zinc–nickel alloy deposition using pulse electrodeposition (ped) technique

Abstract

Zinc–nickel alloy was electrodeposited on stainless steel using pulse current deposition (PED) from a chloride–sulphate bath. Duty cycles were varied between 10 and 80% and frequency was changed from 10 to 100 Hz. The deposit characteristics were analysed using SEM, XRD and AFM and the results are presented in this paper. The corrosion resistance of zinc–nickel alloy deposited from direct current deposition (DCD) has been compared with that of the deposit obtained by pulse current using the electrochemical impedance spectroscopy method.     

Atomic Force Microscope Cantilever Flexural Stiffness Calibration: Toward a Standard Traceable Method

The evolution of the atomic force microscope into a useful tool for measuring mechanical properties of surfaces at the nanoscale has spurred the need for more precise and accurate methods for calibrating the spring constants of test cantilevers. Groups within international standards organizations such as the International Organization for Standardization and the Versailles Project on Advanced Materials and Standards (VAMAS) are conducting studies to determine which methods are best suited for these calibrations and to try to improve the reproducibility and accuracy of these measurements among different laboratories. This paper expands on a recent mini round robin within VAMAS Technical Working Area 29 to measure the spring constant of a single batch of triangular silicon nitride cantilevers sent to three international collaborators. Calibration techniques included reference cantilever, added mass, and two forms of thermal methods. Results are compared to measurements traceable to the International System of Units provided by an electrostatic force balance. A series of guidelines are also discussed for procedures that can improve the running of round robins in atomic force microscopy.     

Microscopic and electrochemical characterization of lead film electrode applied in adsorptive stripping analysis

Lead film electrodes (PbFEs) deposited in situ on glassy carbon or carbon paste supports have recently found application in adsorptive stripping voltammetric determination of inorganic ions and organic substances. In this work, the PbFE, prepared in ammonia buffer solutions, was investigated using scanning electron microscopy, atomic force microscopy and various voltammetric techniques. The microscopic images of the lead films deposited on the glassy carbon substrate showed a considerable variability in microstructure and compactness of the deposited layer depending on the selected experimental conditions, such as the concentration of Pb(II) species, the nucleation and deposition potential, and the time applied. The catalytic adsorptive systems of cobalt and nickel in a solution containing 0.1 ammonia buffer, 2.5 × 10⁻⁵ M nioxime and 0.25 M NaNO₂ were employed to investigate the electrochemical characteristics and utility of the in situ prepared lead films.The optimal parameters, i.e. the lead concentration in the solution, the procedure of film removal, and the time and potential of lead nucleation and film deposition for the adsorptive determination of metal traces, were selected, resulting in the very good reproducibility (RSD = 4.2% for 35 scans) of recorded signals. The voltammetric utility of the lead film electrode was compared to that of glassy carbon, mercury film and bismuth film electrodes, and was subsequently evaluated as superior.     

Atomic force microscopy: influence of air drying and fixation on the morphology and viscoelasticity of cultured cells

The influence of fixation, air-drying and liquid-imaging on the morphology as well as on the viscoelasticity of malignant mesothelioma cells was studied by atomic force microscopy. In this study, dehydrated cells were more easily scanned and offered faster data recording than hydrated cells. However, the influence of fixation strength was more noticeable. Strong fixation induced flattening of the cytoplasm and loss of nuclear structure, resulting in a clearly visible cytoskeleton which could be easily seen as fibres orientated in the direction of the cell growth. By contrast, the morphology of hydrated cells was influenced to a lesser degree on fixation and showed an overall 'rounding' of the surface with vague, ill-defined structures. Nuclear areas of these samples were difficult to image.
Viscoelasticity measurements also exhibited large differences. Dehydrated cells were much harder and showed a uniform indentation profile over the whole cell that was independent of fixation. Indentation on hydrated cells was large and depended on the height of the measuring spot, the submembranous structure and, to a lesser extent, on fixation. To calculate an overall 'cellular' viscoelasticity, different methods were tested on these samples. Indentations of multiple, randomly chosen points, covering the whole cell, were measured and averaged to yield a mean indentation score. We avoided the thin and shadowed areas since it was shown that these regions were less suited for measuring. Using this design, large viscoelasticity differences were found, on which the influence of the external parameters could be shown. In another set-up, layered imaging was tried. However, long data acquisition times caused cellular activation and rearrangement, making this scanning mode unsatisfactory.     

Adsorption structure and adhesion strength of aqueous copolymer lubricant films on Si surface

The adsorption structure of aqueous triblock copolymer polypropylene oxide‐polyethylene oxide‐polypropylene oxide, PPO‐PEO‐PPO, on the Si surface was studied using neutron reflectometer. It is found that PEO blocks formed the outer layer of the adsorbed PPO‐PEO‐PPO film, while PPO blocks formed the inner layer and served as the anchor blocks. The adhesion strength of adsorbed PPO‐PEO‐PPO copolymer film was evaluated using atomic force microscopy and scratch tests. The results revealed that the molecular structure of triblock copolymer had a considerable effect on the adhesion strength. The triblock copolymer with a longer PPO chain and a higher weight percentage of PPO exhibited stronger adhesion and better lubrication performance.     

An AFM Study of corrosion on rigid magnetic disks

The corrosion susceptibility of a cobalt-based magnetic alloy as a function of overcoat film thickness at 20 °C and 50% relative humidity is investigated using atomic force microscopy. The overcoat films include ion beam-deposited nitrogenated carbon (IBDN), and sputter-deposited silicon carbide (SiC) and silicon nitride (SiN_x). In all cases, corrosion decreases with increasing overcoat film thickness. The critical overcoat film thickness for corrosion inhibition is approximately 25, 25 and 20 Å for IBDN, SiC and SiN_x, respectively. However, larger corrosion particles are found for IBDN and SiC with increasing thickness just below the critical thickness for coverage.     

γ（fcc）→α（bcc）马氏体相变表面浮凸的AFM观察与定量分析

利用原子力显微镜（AFM）及扫描电镜（SEM）观察并定量分析了γ(fcc)→α（bcc)马氏体相变的表面浮凸。结果表明：{259}f马氏体表面浮凸为双倾动、帐篷（∧）型，{557}f马氏体的表达浮凸为“孤立岛状”浮凸群，{225}f马氏体表面浮凸为具有层状结构的“三角形”浮凸群；{259}f马氏体表面浮凸的宽度、高度及浮凸角度均大于{225}f马氏体“三角形”浮凸群，{557}f马氏体表面浮凸群的高度最小，其浮凸角也最小。