静电纺丝技术在处理重金属离子方面的研究进展

纳米材料作为一种新兴的材料近年来越来越多地用于重金属离子的去除,而静电纺丝技术是制备纳米纤维最有效最直接的方法.静电纺丝纳米纤维具有纤维直径小、比表面积大、孔隙率高、吸附性能强等优点.主要介绍了静电纺丝纳米纤维膜近年来在处理重金属离子方面的一些研究进展,通过对纳米纤维进行官能团改性、加入无机物等方法制备复合纳米纤维膜已经成为近几年研究的热点.     

同轴射流技术制备纳米复合材料研究进展

简要介绍了基于电流体动力学射流技术的静电纺丝和静电喷涂的基本原理和发展过程,重点讨论了两种同轴射流技术——同轴静电纺丝和同轴静电喷涂技术的研究现状,包括纳/微米包囊、壳-芯结构的纳米纤维和中空纳米纤维或纳米管的制备。介绍了该技术在药物释放体系、组织工程支架、载药医用敷料和缝合线等方面的潜在应用前景,并对其未来发展进行了展望。      

低压静电纺丝最新研究进展

静电纺丝法是目前公认的制备纳米纤维最为有效简易的方法。制备的一维纳米材料(直径在几个微米到几个纳米之间)具备独特的光、电、磁等特性。因而近年来,静电纺丝技术成为研究热点。但是电纺过程需提供高压静电,会带来系列的安全及能耗问题。针对工业化批量生产纳米纤维及近场纺丝对纤维的可控性问题,提出低压静电纺丝概念。文章综述了目前报道的关于低压电纺有代表性的方法。     

静电纺丝技术在超级电容器中的应用

静电纺丝是一种新型的非纺织成丝技术,具有适用材料体系广泛、纤维尺寸结构可控、工艺简便等特点,是制备连续纳米纤维的重要方法.静电纺丝技术制备的纳米纤维薄膜因具有巨大的纳米表面和网状孔隙结构可调等优势,在超级电容器领域显示出诱人的应用前景.综述了近年来静电纺丝技术在超级电容器电极材料和隔膜材料方面的研究进展,介绍了碳基、金属氧化物和聚合物电极材料高活性纳米纤维的制备方法及电化学行为,以及静电纺丝无纺布作为隔膜材料显示出的巨大优势,并总结了制约静电纺丝走向商业化的不利因素,如产率低、薄膜强度不足、喷丝不稳定等,最后介绍了近年来静电纺丝技术在结构可控、规模化制备的产业进展,并展望了其在超级电容器领域中的商业化应用前景.     

基于静电纺丝制备中空纳米纤维的研究进展

中空纳米纤维具有独特的中空结构和较大的比表面积，在吸附、催化、电化学、医药等领域具有广阔的应用前景。静电纺丝技术是制备中空纳米纤维的有效手段。随着静电纺丝工艺的不断成熟，利用静电纺丝大规模制备中空纳米纤维提上了日程。首先详细介绍了基于静电纺丝技术制备中空纳米纤维的原理和方法，探讨了现阶段基于静电纺丝技术大规模制备中空纳米纤维存在的问题以及研究现状，总结了中空纳米纤维的应用进展，最后指出了中空纳米纤维的发展方向，为推动中空纳米纤维的大规模制备及应用奠定基础。     

静电纺丝法制备氧化物纳米纤维及其气敏特性

静电纺丝技术由于简单的装置和制备过程,以及所使用材料的多样和应用领域的广泛,被认为是制备纳米纤维材料最具发展潜力的方法.简述了静电纺丝技术和影响纺丝质量的相关因素;介绍了静电纺丝制备半导体氧化物纳米纤维的方法及纳米纤维在气体传感器领域的应用;比较了几种纳米纤维和纳米线纳米棒等气敏元件的敏感特性;最后分析了纳米纤维具有优...     

电纺丝技术制备金纳米粒子/聚合物复合纳米纤维的研究进展

静电纺丝技术是通过高压静电来制备连续的聚合物纳米纤维的重要方法.近年来,在电纺丝研究领域中,人们关注的焦点是利用此技术制备无机/有机纳米复合材料.金纳米粒子/高分子复合物由于具有独特的光、电性能引起了材料工作者的关注,综述了运用电纺丝技术制备金纳米粒子/高分子复合物的研究进展.     

静电纺丝制备纳米纤维及其装置的研究进展

静电纺丝技术是一种简单有效的制备纳米纤维的新方法.评述了静电纺丝制备不同类型纳米纤维的研究动态,并着重概述了其装置设计和改进的研究进展.相关研究表明,调整接收装置和液体传送装置,以及采用多喷头组合的方式有望成为电纺丝可控制备纳米纤维及其产业化的有效手段.     

静电纺丝技术制备纤维的研究

静电纺丝技术是目前制备直径几十纳米至几微米聚合物纤维的主要方法之一,本文简述了静电纺丝法的背景及基本原理,阐述了影响纤维制备的主要因素,介绍了静电纺丝法制备纳米纤维的种类及发展现状,以及在过滤介质材料、电子光学材料、超疏水性材料、生物医用功能材料、增强复合材料等方面的应用,最后对电纺纳米纤维的发展方向进行了展望.     

静电纺技术在耐高温纤维材料领域研究进展

耐高温纤维在高温过滤膜、锂电池隔膜以及高温催化等方面有着良好的应用。结合纳米纤维高孔隙率、高比表面积等优点,将这些纤维原料经过静电纺丝技术制备成纳米纤维,应用于工业、国防、医疗、环境保护等领域已成为当今材料科学的研究热点。重点综述了静电纺丝技术制备耐高温性能纳米纤维材料的研究进展,如静电纺芳纶、聚酰亚胺、聚苯并咪唑、含氟高分子等聚合物纳米纤维及陶瓷无机纳米纤维等,为进一步开展静电纺丝制备耐高温纳米纤维的研究和应用提供参考。     

Study of GaAs and GaN based heterostructure surfaces and interfaces using ion beams and other complementary techniques

GaAs and GaN semiconductors and their heterostructures have been of interest for a few years now, because of their promising applications. Ion beams and other complimentary techniques are used for characterization of the surface and interfaces, to understand the novel properties of these materials. In this work we have reported the use of complimentary techniques like high-resolution X-ray diffraction (HRXRD), Rutherford backscattering/channelling (RBS/C), atomic force microscopy (AFM), and transmission electron microscopy (TEM) for characterization of these materials. We have studied InGaAs/GaAs heterostructures of various thicknesses by RBS/C, HRXRD, AFM, and TEM before and after irradiation. Bulk epitaxial layers of GaN grown on sapphire with and without AlN cap layer were characterized by HRXRD and AFM while the AlGaN/GaN heterostructures were characterized by RBS/C. The results are analyzed by taking account of the information extracted from these complementary techniques.     

Trace uranium analysis by isotope dilution alpha and mass spectrometry and comparison with other techniques

In this paper uranium determination by isotope dilution mass (MSID) and alpha spectrometry (ASID) using ²³³U as an isotope diluent is discussed. In addition, a new form of MSID employing two tracers (²³⁵U and ²³³U) is developed, where two independent uranium values are obtained for single dilution. The precision and accuracy of each technique are evaluated by comparison with other techniques like X-ray fluorescence and instrumental neutron activation analysis. The techniques, employed here for geological samples, can easily be adapted for environmental materials.     

Folding 2D Structures into 3D Configurations at the Micro/Nanoscale: Principles,Techniques, and Applications

Compared to their 2D counterparts, 3D micro/nanostructures show larger degrees of freedom and richer functionalities; thus, they have attracted increasing attention in the past decades. Moreover, extensive applications of 3D micro/nanostructures are demonstrated in the fields of mechanics, biomedicine, optics, etc., with great advantages. However, the mainstream micro/nanofabrication technologies are planar ones; therefore, they cannot be used directly for the construction of 3D micro/nanostructures, making 3D fabrication at the micro/nanoscale a great challenge. A promising strategy to overcome this is to combine the state‐of‐the‐art planar fabrication techniques with the folding method to produce 3D structures. In this strategy, 2D components can be easily produced by traditional planar techniques, and then, 3D structures are constructed by folding each 2D component to specific orientations. In this way, not only will the advantages of existing planar techniques, such as high precision, programmable patterning, and mass production, be preserved, but the fabrication capability will also be greatly expanded without complex and expensive equipment modification/development. The goal here is to highlight the recent progress of the folding method from the perspective of principles, techniques, and applications, as well as to discuss the existing challenges and future prospectives.     

Simultaneous measurements of normal spectral emissivity by spectral radiometry and laser polarimetry at high temperatures in millisecond-resolution pulse-heating experiments: Application to molybdenum and tungsten

Spectral radiometry and laser polarimetry are two independent techniques for the measurement of spectral emissivity of materials. In this paper, a high-speed system is described for the rapid measurement of normal spectral emissivity of a specimen based on the simultaneous utilization of the two techniques. One of the goals of this work to ascertain the accuracy of the laser polarimetry technique in measurement of normal spectral emissivity at high temperatures. To accomplish this goal, the normal spectral emissivities, in the vicinity of 0.633m, of molybdenum and tungsten were measured by the two techniques over the temperature range 2000 to 2600 K. The results obtained by the two techniques are in agreement within 1%. The total uncertainty (two-standard deviation level) in measurement of emissivity by either spectral radiometry or laser polarimetry technique is estimated to be not more than + 2%.     

Comparing safety analysis techniques

In process industry Safety Instrumented Systems (SIS) and Emergency Shutdown Systems (ESD) are very important for the management/reduction of risk. In new standards (e.g. Ref. [1]) on functional safety of electrical/electronic/programmable electronic safety-related systems a quantification of the achieved safety is often required. These new standards do not prescribe how to calculate the achieved safety. Only guidelines and recommendations are given. The problem with this approach is that all kinds of different analysis techniques will be used and in industry the results of the analysis will be compared. These different analysis techniques all use different methodologies and assumptions, which implies that the results may not be comparable. In this paper an approach for comparing different analysis techniques and the qualitative and quantitative results from this comparison are described. The author suggests that, because of the differences in the analysis techniques, one analysis technique is to be preferred. The Enhanced Markov Analysis technique, described in this paper, could be used for this purpose because it covers most aspects relevant for quantification of safety.     

Criticality accident dosimetry systems: an international intercomparison at the SILENE reactor in 2002

In criticality accident dosimetry and more generally for high dose measurements, special techniques are used to measure separately the gamma ray and neutron components of the dose. To improve these techniques and to check their dosimetry systems (physical and/or biological), a total of 60 laboratories from 29 countries (America, Europe, Asia) participated in an international intercomparaison, which took place in France from 9 to 21 June 2002, at the SILENE reactor in Valduc and at a pure gamma source in Fontenay-aux-Roses. This intercomparison was jointly organised by the IRSN and the CEA with the help of the NEA/OCDE and was partly supported by the European Communities. This paper describes the aim of this intercomparison, the techniques used by the participants and the two radiation sources and their characteristics. The experimental arrangements of the dosemeters for the irradiations in free air or on phantoms are given. Then the dosimetric quantities measured and reported by the participants are summarised, analysed and compared with the reference values. The present paper concerns only the physical dosimetry and essentially experiments performed on the SILENE facility. The results obtained with the biological dosimetry are published in two other papers of this issue.     

碳化硅增强铝基复合材料连接技术研究进展

综述了SiC增强铝基复合材料(包括SiCp／AlMMC和SiCw／AlMMC)连接技术的研究现状,分析了连接中存在的问题。简单介绍了用于该复合材料连接的传统焊接方法,如熔化焊、固相连接、钎焊等。重点介绍了SiC颗粒及SiC纤维增强铝基复合材料的一些新型连接技术,并展望了SiC增强铝基复合材料连接技术的发展方向。     

Analysis of inclusions in spring steel using scanning electron microscopy and Auger spectroscopy

Different electron beam based techniques such us SEM/EDS and AES are very similar with regard to their imaging capabilities, but there are significant differences in the compositional information they can provide about the sample. In order to determine the usefulness of a technique for the identification of inclusions in spring steel the SEM/AES analysis techniques were used and are shown to be well suited for characterizing of these inclusions. From the results it was possible to evaluate the nature of inclusions, their location, size and chemical composition. It is evident from this study that applications of different techniques in inclusion determination are more representative and reflect inclusion size distribution in sample more objectively.     

Designing techniques for systemic impact: lessons from C-K theory and matroid structures

As underlined in Arthur’s book “the nature of technology”, we are very knowledgeable on the design of objects, services or technical systems, but we don’t know much on the dynamics of technologies. Still contemporary innovation often consists in designing techniques with systemic impact. They are pervasive—both invasive and perturbing—and they recompose the family of techniques. Can we model the impact and the design of such techniques? More specifically: how can one design generic technology, i.e. a single technology that provokes a complete reordering of families of techniques? Advances in design theories open new possibilities to answer these questions. In this paper, we use C-K design theory and a matroid-based model of the set of techniques to propose a new model (C-K/Ma) of the dynamics of techniques, accounting for the design of generic technologies. We show that: (1) C-K/Ma accounts for basic phenomena in the design of pervasive (and non-pervasive) techniques, in particular for generic techniques. (2) C-K/Ma, when applied iteratively, helps to propose new laws for the dynamics of techniques and helps to build strategic alternatives in the design of techniques. Moreover, C-K/Ma contributes to design theory since it provides some basic quantifiers and operations that could lead to a computational model of the process of designing techniques with systemic impact.     

How to Apply Nonlinear Subspace Techniques to Univariate Biomedical Time Series

In this paper, we propose an embedding technique for univariate single-channel biomedical signals to apply projective subspace techniques. Biomedical signals are often recorded as 1-D time series; hence, they need to be transformed to multidimensional signal vectors for subspace techniques to be applicable. The transformation can be achieved by embedding an observed signal in its delayed coordinates. We propose the application of two nonlinear subspace techniques to embedded multidimensional signals and discuss their relation. The techniques consist of modified versions of singular-spectrum analysis (SSA) and kernel principal component analysis (KPCA). For illustrative purposes, both nonlinear subspace projection techniques are applied to an electroencephalogram (EEG) signal recorded in the frontal channel to extract its dominant electrooculogram (EOG) interference. Furthermore, to evaluate the performance of the algorithms, an experimental study with artificially mixed signals is presented and discussed.