ZnS nanoparticle synthesis and stability of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) under glow discharge plasma

Ionic liquid glow discharge electrolysis for nanoparticle synthesis is an emerging nanomaterials processing technology and the stability of ionic liquid when they are in contact with plasma is an important issue. This paper discusses the stability of [BMIM][BF4] after exposing this ionic liquid to glow discharge plasma and the synthesis of cubic crystalline ZnS nanoparticles by plasma electrochemical method. Stability of the ionic liquid after plasma exposure to 20 min at 250 V is explained by their FTIR spectra and found that the ionic liquid is stable even after the plasma exposure.     

Life-cycle assessment of engineered nanomaterials: a literature review of assessment status

The filtration of airborne nanoparticles is an important control technique as the environmental, health, and safety impacts of nanomaterials grow. A review of the literature shows that significant progress has been made on airborne nanoparticle filtration in the academic field in the recent years. We summarize the filtration mechanisms of fibrous and membrane filters; the air flow resistance and filter media figure of merit are discussed. Our review focuses on the air filtration test methods and instrumentation necessary to implement them; recent experimental studies are summarized accordingly. Two methods using monodisperse and polydisperse challenging aerosols, respectively, are discussed in detail. Our survey shows that the commercial instruments are already available for generating a large amount of nanoparticles, sizing, and quantifying them accurately. The commercial self-contained filter test systems provide the possibility of measurement for particles down to 15 nm. Current international standards dealing with efficiency test for filters and filter media focus on measurement of the minimum efficiency at the most penetrating particle size. The available knowledge and instruments provide a solid base for development of test methods to determine the effectiveness of filtration media against airborne nanoparticles down to single-digit nanometer range.     

大气压电解液阴极辉光放电发射光谱检测水体中的金属残留

水环境中的金属残留严重威胁人类的健康安全,急需快速、高效的金属残留检测技术。文章报道了自行建立的大气压电解液阴极辉光放电发射光谱装置。利用待测液体作为放电阴极进行大气压辉光放电实现了水体中金属离子的痕量检测。对配制的标准样品进行了定量测量,基于背景发射光谱的3σ计算,获得了大气压电解液阴极辉光放电光谱装置对Na, Li, Cu, Pb和Mn等5种金属元素的检测限,分别为0.008, 0.005, 1.1, 2.06和1.95 mg·L-1。该装置在金属残留的实时在线检测领域具有应用前景。     

Method for producing nanomaterials in the plasma of a low-pressure pulsed arc discharge

A new method for the production of nanomaterials in the plasma of a low-pressure arc discharge is developed and experimentally studied. This method can be used to synthesize nanoparticles 5–10 nm in size with a narrow size distribution. In this method, a low-pressure arc discharge is used to melt a material, to disperse the molten material, to deliver liquid material droplets to the plasma, to cool the liquid nanoparticles forming in the plasma up to their solidification, and to deposit the solidified nanoparticles onto a substrate.     

The influence of a radial magnetic field on current-voltage characteristics of toroidal glow discharge

The present paper deals with the influence of a radial magnetic field on different regions of the toroidal glow discharge and with the subsequent changes of the current-voltage characteristics. From the above it is clear that when studying the influence of a transverse magnetic field on the glow discharge it is necessary to understand that the discharge is not a homogeneous unit and the change of current-voltage characteristics involves the total sum of changes of the properties in different regions of the discharge.     

Nanoscale metal oxide particles produced in the plasma discharge in the liquid phase upon exposure to ultrasonic cavitation. 1. Method for producing particles

It is shown that a new form of the plasma discharge with bulk glow throughout the space between electrodes and an descending current-voltage characteristic, occurring in liquid in an ultrasonic field with an intensity above the cavitation threshold, can be efficiently used to initiate the various physical and chemical processes. In such an acoustic plasma discharge, nanoparticles of oxides of various metals, i.e., aluminum, copper, tin, iron, titanium, indium, zinc, molybdenum, and others, are synthesized with controllable particle shape and size and narrow size distribution. Micrographs of some nanoparticles are presented. The difference in luminescence of particles produced in the absence and presence of cavitation is shown.     

The Hollow Cathode Discharge as a Spectrochemical Emission Source

Abstract

The hollow cathode discharge (HCD), a specialized type of glow discharge, has been the subject of investigations by physicists (in particular) and chemists for over a half century. Several hundred literature reports may be found concerning various aspects of the HCD. Despite this, many analytical chemists today would consider the HCD as merely a sharp line source for atomic absorption spectrometry (AAS). While this is certainly its most important present application, the HCD has a long history as a spectrochemical emission source allowing direct excitation and analysis of samples. Excellent sensitivities have been reported, but experimental difficulties, including construction of a demountable hollow cathode tube, have limited overall past acceptance of the HCD as an analytical emission technique. However, the current interest by analytical spectroscopists in new methods of atomization and excitation has revived interest in glow discharges. Also, the commercial availability of two demountable hollow cathode tubes and associated vacuum systems now allows easy accessibility to the technique.     

Theory of a normal high-pressure glow discharge

In the present work, a theoretical model considering the processes of generation and losses of charged particles in the cathode region of a glow discharge in the drift approximation for ion and electron motion is developed. Exact analytical solutions, which can be used to calculate the current-voltage characteristics of the glow discharge in an arbitrary gas with the known Townsend ionization coefficient, are derived. The calculated parameters of the normal glow discharge (the current density, discharge burning voltage, and width of the space charge region) for different gases are in good agreement with the available experimental data. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 71–77, February, 2006.     

Sonoproduction of nanobiomaterials – A critical review

Ultrasound (US) demonstrates remarkable potential in synthesising nanomaterials, particularly nanobiomaterials targeted towards biomedical applications. This review briefly introduces existing top-down and bottom-up approaches for nanomaterials synthesis and their corresponding synthesis mechanisms, followed by the expounding of US-driven nanomaterials synthesis. Subsequently, the pros and cons of sono-nanotechnology and its advances in the synthesis of nanobiomaterials are drawn based on recent works. US-synthesised nanobiomaterials have improved properties and performance over conventional synthesis methods and most essentially eliminate the need for harsh and expensive chemicals. The sonoproduction of different classes and types of nanobiomaterials such as metal and superparamagnetic nanoparticles (NPs), lipid- and carbohydrate-based NPs, protein microspheres, microgels and other nanocomposites are broadly categorised based on the physical and/or chemical effects induced by US. This review ends on a good note and recognises US-driven synthesis as a pragmatic solution to satisfy the growing demand for nanobiomaterials, nonetheless some technical challenges are highlighted.     

Occupational exposure limits for nanomaterials: state of the art

Assessing the need for and effectiveness of controlling airborne exposures to engineered nanomaterials in the workplace is difficult in the absence of occupational exposure limits (OELs). At present, there are practically no OELs specific to nanomaterials that have been adopted or promulgated by authoritative standards and guidance organizations. The vast heterogeneity of nanomaterials limits the number of specific OELs that are likely to be developed in the near future, but OELs could be developed more expeditiously for nanomaterials by applying dose–response data generated from animal studies for specific nanoparticles across categories of nanomaterials with similar properties and modes of action. This article reviews the history, context, and approaches for developing OELs for particles in general and nanoparticles in particular. Examples of approaches for developing OELs for titanium dioxide and carbon nanotubes are presented and interim OELs from various organizations for some nanomaterials are discussed. When adequate dose–response data are available in animals or humans, quantitative risk assessment methods can provide estimates of adverse health risk of nanomaterials in workers and, in conjunction with workplace exposure and control data, provide a basis for determining appropriate exposure limits. In the absence of adequate quantitative data, qualitative approaches to hazard assessment, exposure control, and safe work practices are prudent measures to reduce hazards in workers.     

Study of the rectangular hollow cathode discharge

The rectangular hollow cathode discharge is studied with respect to the applicability of similarity mechanisms analogously to other gas discharge types. Probe characteristics of the discharge are measured, the conditions of steady and continuous discharge glow in the cathode cavity are determined.     

Using sonochemistry for the fabrication of nanomaterials

One of the reasons for the huge interest in nanomaterials originated because of the prohibitive price that commercial companies have to pay for introducing new materials into the market. Nanotechnology enables these companies to obtain new properties using old and recognized materials by just reducing their particle size. For these known materials no government approval has to be obtained. Thus, the interest in nanomaterials has led to the development of many synthetic methods for their fabrication. Sonochemistry is one of the earliest techniques used to prepare nanosized compounds. Suslick, in his original work, sonicated Fe(CO)5 either as a neat liquid or in a decalin solution and obtained 10-20 nm size amorphous iron nanoparticles. A literature search that was conducted by crossing Sono* and Nanop* has found that this area is expanding almost exponentially. It started with two papers published in 1994, two in 1995, and increased to 59 papers in 2002. A few authors have already reviewed the fields of Sono and Nano. It should be mentioned that in 1996, Suslick et al. published an early review on the nanostructured materials generated by ultrasound radiation. Suslick and Price have also reviewed the application of ultrasound to materials science. This review dealt with nanomaterials, but was not directed specifically to this topic. The review concentrated only on the sonochemistry of transition metal carbonyls and catalytic reactions that involve the nanoparticles resulting from their sonochemical decomposition. Grieser and Ashokkumar have also written a review on a similar topic. A former coworker, Zhu, has recently submitted for publication a review article entitled "Novel Methods for Chemical Preparation of Metal Chalcogenide Nanoparticles" in which he reviews three synthetic methods (sonochemistry, sonoelectrochemistry, and microwave heating) and their application in the synthesis of nanosized metal chalcogenides. Although still unpublished, I myself have recently written a review discussing novel methods (sonochemistry, microwave heating, and sonoelectrochemistry) for making nanosized materials. The current review will: (1) Present the four main advantages that sonochemistry has over other methods related to materials science and nanochemistry; (2) concentrate on the more recent (2003) literature that was not reviewed in the previously-mentioned reviews, and (3) focus on a specific question, such as what is the typical shape of products obtained in sonochemistry? This review will not survey the literature related to sonoelectrochemistry.     

High pressure structural phase transitions of TiO_2 nanomaterials

Recently, the high pressure study on the TiO_2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO_2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO_2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO_2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO_2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets,and nanoporous materials, and pressure-induced amorphization(PIA) and polyamorphism in ultrafine nanoparticles and TiO_2-B nanoribbons. Various TiO_2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO_2 nanoribbons, α-PbO_2-type TiO_2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO_2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO_2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications.     

针-板DBD微流注与微辉光交替生成的机理研究

在介质阻挡放电体系中产生辉光放电可以有效的提高放电体系产生高能电子的性能, 为等离子体化学反应提供更加丰富的活性粒子.本文对针-板介质阻挡放电体系下的放电模式进行了研究,实验发现放电正负半周期表现出不同的放电模式, 激励电压为3 kV时放电正负半周期分别为微流注放电和电晕放电(或者Trichel脉冲放电),激励电压为6 kV时放电正负半周期分别为微流注放电和微辉光放电.微辉光放电形貌具有与典型辉光放电相同的分层次放电结构, 分析了激励电压6 kV时的放电过程,认为足够强的阴极电场强度和裸露针状电极形成的有效的二次电子发射过程是形成微辉光放电的主要因素,绝缘介质层的存在避免了微辉光放电向弧光放电过渡.     

Overview of nano-drugs characteristics for clinical application: the journey from the entry to the exit point

The ever-increasing number of diseases worldwide requires comprehensive, efficient, and cost-effective modes of treatments. Among various strategies, nanomaterials fulfill most of these criteria. The unique physicochemical properties of nanoparticles have made them a premier choice as a drug or a drug delivery system for the purpose of treatment, and as bio-detectors for disease prognosis. However, the main challenge is the proper consideration of the physical properties of these nanomaterials, while developing them as potential tools for therapeutics and/or diagnostics. In this review, we focus mainly on the characteristics of nanoparticles to develop an effective and sensitive system for clinical purposes. This review will present an overview of the important properties of nanoparticles, through their journey from its route of administration until disposal from the human body after accomplishing targeted functionality. We have chosen cancer as our model disease to explain the potentiality of nano-systems for therapeutics and diagnostics in relation to several organs (intestine, lung, brain, etc.). Furthermore, we have discussed their biodegradability and accumulation probability which can cause unfavorable side effects in healthy human subjects.     

Recent Advances in Analytical Applications of Nanomaterials in Liquid-Phase Chemiluminescence

Abstract

In recent years, many nanomaterials-assisted chemiluminescence (CL) systems have been developed to improve the sensitivity and to expand the scope of their analytical applications. In these new systems, nanomaterials participate in CL reactions as catalysts, labels, reductants, luminophors, or energy acceptors. This review mainly focuses on the recent analytical applications of metal nanoparticles, magnetic nanoparticles, quantum dots (QDs), and carbon-based nanomaterials (carbon nanotubes and graphene) in liquid-phase CL systems. Recent advances in electrochemiluminescence based on nanotechnology and its analytical applications, especially in immunoassay, DNA analysis, and other biological analyses, are also summarized. Finally, we discuss some critical challenges in this field and speculate about their solutions. A total of 177 references mainly in the last 5 years are included in this review.     

微乳液技术制备纳米材料

微乳液是表面活性剂、油相和水相形成的热力学稳定的各向同性的单分散体系,其分散质点为纳量级,它为纳米材料的制备提供理想的模板和微环境,介绍微乳液制备纳米材料的方法和影响因素以及微乳液法制备催化剂、超导体、半导体及磁性等材料的研究进展。     

Plasma discharge with bulk glow in the liquid phase exposed to ultrasound

It is shown that a specific form of the electric discharge with bulk glow in the entire space between electrodes and an increasing current-voltage characteristic inherent to the anomalous glow discharge in gas can exist in a liquid exposed to an intense ultrasonic field above the cavitation threshold. Such a discharge can be initiated between planar or rod electrodes in liquid in the mode of developed cavitation excited by an ultrasonic acoustic field. It is found that a plasma pinch is formed during cavitation between electrodes immersed into liquid. The pinch is stable at relatively low voltages (??30?C60 V) and currents (4?C8 A).     

Phase transition and mechanical properties of tungsten nanomaterials from molecular dynamic simulation

Molecular dynamic simulation is used to systematically find out the effects of the size and shape of nanoparticles on phase transition and mechanical properties of W nanomaterials. It is revealed that the body-centered cubic (BCC) to face-centered cubic (FCC) phase transition could only happen in cubic nanoparticles of W, instead of the shapes of sphere, octahedron, and rhombic dodecahedron, and that the critical number to trigger the phase transition is 5374 atoms. Simulation also shows that the FCC nanocrystalline W should be prevented due to its much lower tensile strength than its BCC counterpart and that the octahedral and rhombic dodecahedral nanoparticles of W, rather than the cubic nanoparticles, should be preferred in terms of phase transition and mechanical properties. The derived results are discussed extensively through comparing with available observations in the literature to provide a deep understanding of W nanomaterials.