Tip-induced large-area oxide bumps and composition stoichiometry test via atomic force microscopy

Using atomic force microscope (AFM) tip, local large-area oxide bumps were induced on a native SiO₂ layer applied with a static 10 V in an ambient surrounding. It can be seen in the backscattered electron (BE) images that the oxide bumps were SiO_x layer, not the native SiO₂ layer. Also, the spectra of energy dispersive X-ray spectrometer (EDS) displayed that the oxide bumps contained oxygen more than did the native SiO₂ layer, indicating that the O/Si ratio of the oxide bump is greater than two. A comparison of the growth rates of the point oxide protrusions on the oxide bumps and on the native SiO₂, can be used to directly determined the composition stoichiometry (the O/Si ratio (=x)) of the oxide bumps.     

Chemical modification of polymeric microchip devices

Analytical polymeric microchips in both fluidic and array formats offer short analysis times, coupling of many sample processing and chemical reaction steps on one platform with minimal sample and reagent consumption, as well as low cost, minimal fabrication times and disposability. However, the invariable bulk properties of most commercial polymers have driven researchers to develop new modification strategies. This article critically reviews the scope and development of chemical modifications of such polymeric chips since 2003. Surface modifications were based on chemical derivatization or activation of surface layers with reagent solutions, reactive gases and irradiation. Bulk modification of polymer chips used newly incorporation of monomers with selective chemical functionalities throughout the bulk polymer material and integrated the chip modification and fabrication into a single step. Such modifications hold a great promise for establishing a true ‘lab-on-chip’ as can be seen from many novel applications for modulating electroosmosis, suppressing protein adsorption in microchip capillary electrophoretic separations, extraction of analytes and for zone-specific binding of enzymes and other biomolecules.     

FTIR-ATR、EDS结合生理特性研究铅胁迫对玉米幼苗的影响

应用X射线能谱(EDS)和傅里叶变换-衰减全反射红外光谱(FTIR-ATR)分析方法结合一些生理指标的变化,研究铅胁迫对玉米幼苗的影响.结果表明,随着Pb2+浓度的升高,抗氧化酶(SOD、CAT、POD)活性均先升高后降低.利用红外光谱检测发现,植物各组分吸收金属前后的峰形基本不变,参与重金属吸附的基团如羟基(3328...     

电镜-能谱仪在柳树叶重金属污染研究中的应用

采用自然干燥、化学处理、冷冻处理3种方法制备待测样本,运用扫描电镜和透射电镜结合X射线能谱仪研究柳树叶肉组织对重金属的累积状况,并定位到栅栏组织的细胞壁,为定性定量以及定位分析组织细胞固定、转移重金属污染探索合适的制样方法.结果表明:(1)重金属Pb、Cu、Cd、Zn在柳树叶肉组织被检测到,并已进入到细胞壁内,同时定量结果显示污染越严重,重金属累积量越多,证明了柳树叶对重金属污染的吸收能力;(2)通过综合比较,认为冷冻处理的样本比较适合进行植物组织微区的元素定性定量以及定位分析,因此推测冷冻制样加冷冻电镜的方法将会最为理想.     

Preparation,characterization and catalytic activity of MoO3/CeO2–ZrO2 solid heterogeneous catalyst for the synthesis of β-enaminones

A series of CeO₂–ZrO₂ with different molybdenum (8–20 wt% MoO₃) loaded materials were prepared by homogeneous co-precipitation followed by impregnation method. The prepared materials were tested for their catalytic activity performance in the synthesis of β-enaminones by condensation of various anilines with dimedone under solvent-free conditions in microwave providing excellent yields within short reaction time. An obtained result reveals that, catalytic activity increases with increase in Mo wt% loading. The particle size of prepared materials was estimated using Debye–Scherrer equation. Particle size increases with increase in Mo wt% loading providing nanosized particle ranging from 7.11 to 42.09 nm. The synthesized materials were characterized by means of X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques.     

Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene – a single atomic layer of graphite – is the newest member in the family of carbon allotropes and has emerged as the “celeb” material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.     

Carbon nanotubes as solid-phase extraction sorbents prior to atomic spectrometric determination of metal species: A review

New materials have significant impact on the development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes – due to their high adsorption and desorption capacities – have been employed as sorption substrates in solid-phase extraction for the preconcentration of metal species from diverse matrices. Looking for successive improvements in sensitivity and selectivity, in the past few years, carbon nanotubes have been utilized as sorbents for solid phase extraction in three different ways: like as-grown, oxidized and functionalized nanotubes. In the present paper, an overview of the recent trends in the use of carbon nanotubes for solid phase extraction of metal species in environmental, biological and food samples is presented. The determination procedures involved the adsorption of metals on the nanotube surface, their quantitative desorption and subsequent measurement by means of atomic spectrometric techniques such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry/mass spectrometry, among others. Synthesis, purification and types of carbon nanotubes, as well as the diverse chemical and physical strategies for their functionalization are described. Based on 140 references, the performance and general properties of the applications of solid phase extraction based on carbon nanotubes for metal species atomic spectrometric determination are discussed.     

磁控溅射制备的AlN薄膜的结构、组分及性能分析

采用DC磁控溅射法,分别在p-Si(111)和玻璃基片上沉积AlN薄膜。利用X射线衍射(XRD)、X射线能谱仪(EDS)、原子力显微镜(AFM)、台阶仪\紫外/可见分光光度计和傅里叶变换红外光谱仪(FTIR)分析了薄膜的结构组分、表面形貌、膜厚、光学性能和红外吸收特性。结果表明:溅射电流对AlN薄膜的生成有很大的影响,当电流增加到0.40A时,薄膜中出现明显的h-AlN(100)和AlN(110)衍射峰;样品的最大高度都小于30nm;样品在250-1000nm波长范围内具有较高的透射率,当溅射电流为0.4A时,薄膜的禁带宽度约为5.94eV;在677.12cm-1处出现强烈的吸收峰。     

波谱仪与能谱仪性能的比较

用实验测量数据对波谱分析与能谱分析这两种技术在元素定性与定量分析方面的性能差异进行了比较,说明各自的长处与不足,为材料科学工作者在分析测试中如何选择提供参考。     

Effect of Electrolytes on Redox Reactivity of Polypyrrole

Doping and dedoping characteristics of polypyrrole (PPy) formed electrochemically have been examined by means of energy-dispersive X-ray spectroscopy (EDS). Dodecylsulfate ions (DS⁻) and perchlorate ions (ClO⁻₄) were embedded simultaneously in PPy when both ions were present on the polymerization of pyrrole. Sequential formation of PPy in the single dopant system allowed PPy/ClO₄ to grow in the bulk of PPy/DS but not vice versa. DS⁻ was embedded not to leave the polymer on reduction but ClO⁻₄ moved in and out of the polymer on redox reaction. Cyclic voltammetry was employed to determine the redox reactivity of PPy in different electrolyte systems. NaClO₄ was a better electrolyte for cyclic redox reaction than LiClO₄ or KClO₄. NaCl was a good electrolyte for cyclic redox reaction but Cl⁻ failed to penetrate in the PPy/DS bulk on reoxidation. The cyclic redox reactivity lasted longest when PPy/DS was redox-cycled sequentially in the NaCl electrolyte system and then in the NaClO₄ system. © 1997 John Wiley & Sons, Ltd.