Conservation of acid waterlogged shipwrecks: nanotechnologies for de-acidification

Preservation of waterlogged wooden artifacts, and in particular ancient wrecks, is a challenge in cultural heritage conservation. Samples, from the Swedish warship Vasa, are under investigation in order to develop innovative methods for wood de-acidification and preservation. The Vasa represents a unique case in the study of ancient wrecks. In the past four years the problem of the acidity of wood emerged as a strong threat to its conservation. The production of sulphuric acid inside the ship wood might be the cause of both chemical damage through the acid hydrolysis of cellulose, and of physical damage of the wood’s pore structure, due to the crystallization of sulphate minerals in the wood pores. In this paper we show that wood acidity can be neutralized by the application of nanoparticles of alkaline-earth carbonates and/or hydroxides. The treatment provides an alkaline reservoir inside the wood. Nanoparticles absorbed in the wood from an alcoholic dispersion adhere to the wood wall and release hydroxyl ions leading to the wood neutralization. Oak and pine samples from the Vasa wreck were characterized and treated with alkaline magnesium or calcium nanoparticle dispersions in non-aqueous solvents. De-acidification was monitored by pH changes and thermal analysis, and all the treated samples were submitted to thermal artificial ageing in order to demonstrate the efficacy of the method. The results obtained opened a new perspective in wood conservation. PACS 81.07.Bc; 81.07.Wx; 82.33.Ln; 83.80.Hj; 81.70.Pg     

Challenges and potential of new approaches for reliability assessment of nanotechnologies

Reliability assessment of components, integrated circuits or micro-assemblied devices, is undoubtedly identified as one of the major factors conditioning the on-going development of microelectronics. In the same way, growing market penetration by nanotechnologies is clearly related to the imperative demonstration of satisfactory built-in operational reliability with respect to actual severe standards. This situation requires a specific effort on built-in reliability. These considerations must be integrated, as early as possible at the beginning of the development ‘top-down’ and the ‘bottom-up’ approaches. Reliability issues cover extremely large scientific fields such as physics, material science, electrical transport, thermal phenomena, coupling interfaces between optics and electronics, statistical models, etc.The objective of this paper deals with the presentation of new, original methodologies for reliability assessment, coming from studies in the IMS Laboratory, in close collaboration with industrial and academic partners. These new approaches are based on the combination of the physical laws of failure, behavioral simulations and statistical methods, adding inevitable parametric dispersions to extrapolate failure rates and lifetime in operating conditions. Some results are presented and analyzed on micro-assemblied technologies and photonic components for high-rate optical links. The main goal is to discuss their potentiality and applicability field with a view to intrinsic nanodevices reliability assessment in operating conditions. To cite this article: L. Béchou et al., C. R. Physique 9 (2008).     

ITER 试验包层模块活化计算与环境安全分析

运用聚变堆放射性计算程序FDKR 和衰变链数据库AFDC-DLIB, 计算了ITER 中国氦冷固态增殖试验包层模块设计中活化产物的放射性、衰变余热和潜在生物危害因子BHP 值。计算结果表明: 对于试验包层模块来说, 在500MW 聚变功率下运行一年, 停堆时的总放射性、余热和BHP 值分别为2. 10× 10¹⁶B_q 、5. 06 × 10^{- 3}MW 和 68. 6km³•( kW) ^{- 1}。结果表明: 中国氦冷实验包层模块不存在突出的安全问题。     

Occupational safety and health criteria for responsible development of nanotechnology

In this study we investigated the release of titanium dioxide (TiO₂), silver (Ag) and silica (SiO₂) engineered nanoparticles (ENPs) from three different paints by using standardized water immersion test for coatings. Fibre-cement panels were coated with paints containing ENPs and then exposed to UV light and abraded to simulate weathering. After the static water immersion test, we observed a very low release of Ti (4–8 μg/l), while the Ag measured in leachates was under detection limit (0.1 μg/l). A small release of Si was measured in leachates, with 73 mg/l of Si released from paints containing SiO₂ ENPs after 120 h of water immersion. The cumulative loss of Si was about 1.8 % with respect to initial amount of Si in paint. Microscopic results highlighted that SiO₂ ENPs are mainly released in form of agglomerates with other particles, and only very few single SiO₂ ENPs were found in leachates. The results confirmed that Si migration is related to immersion cycles (wetting and drying cycles) of tested paints.     

HLT/SR2000环境试验装置制冷系统设计

制冷系统是环境试验装置的核心部分之一。文中对HLT/SR2000环境试验装置制冷系统组成和原理进行了概述,并给出了制冷系统负荷及状态点热力学参数的计算方法,对压缩机选型进行了简要说明。经过实际运行表明,该制冷系统各项指标均满足设计要求。经过第三方检测温度各项指标均优于用户要求。     

激光驾束制导武器接收系统模拟测试方法的研究

通过对激光驾束制导原理的分析,设计一种基于复杂可编程逻辑器件(CPLD)和单片机的脉冲发生器,实现了与激光驾束制导光场信息规律一致的电脉冲信号的产生,并通过设计快速开关驱动电路和功率控制电路对电脉冲信号进行功率放大,驱动高响应速度的准激光发光二极管,有效地模拟了激光驾束制导的光场信息,从而为解决激光驾束制导武器接收系统的接收灵敏度,以及偏航和俯仰制导精度等参数的室内非接触测试问题提供了一个有效的方法。对该模拟测试装置的误差进行了分析,提出了减小误差的方法。     

Analysis of radiation environmental safety for China's Spallation Neutron Source(CSNS)

The China Spallation Neutron Source(CSNS)is going to be located in Dalang Town,Dongguan City in the Guangdong Province.In this paper we report the results of the parameters related with environment safety based on experiential calculations and Monte Carlo simulations.The main project of the accelerator is an under ground construction.On top there is a 0.5 m concrete and 5.0 m soil covering for shielding,which can reduce the dose out of the tunnel's top down to 0.2 μSv/h.For the residents on the boundary of the CSNS,the dose produced by skyshine,which is caused by the penetrated radiation leaking from the top of the accelerator,is no more than 0.68 μSv/a.When CSNS is operating normally,the maximal annual effective dose due to the emission of gas from the tunnel is 2.40×10-3 mSv/a to the public adult,and 2.29×10-3 mSv/a to a child,both values are two orders of magnitude less than the limiting value for control and management.CSNS may give rise to an activation of the soil and groundwater in the nearest tunnels,where the main productions are 3H,7Be,22Na,54Mn,etc.But the specific activity is less than the exempt specific activity in the national standard GB13376-92.So it is safe to say that the environmental impact caused by the activation of soil and groundwater is insignificant.To sum up,for CSNS,as a powerful neutron source device,driven by a high-energy high-current proton accelerator,a lot of potential factors affecting the environment exist.However,as long as effective shieldings for protection are adopted and strict rules are drafted,the environmental impact can be kept under control within the limits of the national standard.     

Occupational safety and health in nanotechnology and Organisation for Economic Cooperation and Development

The Organization for Economic Cooperation and Development (OECD), an intergovernmental organization, is playing a critical global role in ensuring that emerging technologies, such as nanotechnology, are developed responsibly. This article describes OECD activities around occupational safety and health of nanotechnology and provides state-of-the-science overview resulting from an OECD workshop on exposure assessment and mitigation for nanotechnology workplace.     

How can nanobiotechnology oversight advance science and industry: examples from environmental,health, and safety studies of nanoparticles (nano-EHS)

Nanotechnology has great potential to transform science and industry in the fields of energy, material, environment, and medicine. At the same time, more concerns are being raised about the occupational health and safety of nanomaterials in the workplace and the implications of nanotechnology on the environment and living systems. Studies on environmental, health, and safety (EHS) issues of nanomaterials have a strong influence on public acceptance of nanotechnology and, eventually, affect its sustainability. Oversight and regulation by government agencies and non-governmental organizations (NGOs) play significant roles in ensuring responsible and environmentally friendly development of nanotechnology. The EHS studies of nanomaterials can provide data and information to help the development of regulations and guidelines. We present research results on three aspects of EHS studies: physico-chemical characterization and measurement of nanomaterials; emission, exposure, and toxicity of nanomaterials; and control and abatement of nanomaterial releases using filtration technology. Measurement of nanoparticle agglomerates using a newly developed instrument, the Universal NanoParticle Analyzer (UNPA), is discussed. Exposure measurement results for silicon nanoparticles in a pilot scale production plant are presented, as well as exposure measurement and toxicity study of carbon nanotubes (CNTs). Filtration studies of nanoparticle agglomerates are also presented as an example of emission control methods.     

Data and modeling of negative ion transport in gases of interest for production of integrated circuits and nanotechnologies

We review techniques to prepare, evaluate and apply sets of cross section and transport data for negative ions that are required for the modeling of collisional non-equilibrium plasmas used for processing of microelectronic circuits. We collect and discuss the transport coefficients and cross section sets.We have compiled data for negative ions in CF₄ and CF₄-related negative ions in rare gases. In addition, we consider data for F⁻ and CF₃⁻ in rare gases. Furthermore, we analyze the cross sections of halogen negative ions in rare gases and other molecules. This is followed by the data for SF₆ related ions in SF₆ and in rare gases. The cross section for scattering of O⁻ in O₂ has been derived from the transport data and used to make calculations of the transport properties. Finally we give a brief discussion of the availability of the data for H⁻ ions in H₂. We have derived cross sections in several cases but the basic aim is to show the basic features of transport coefficients. In particular we discuss the need to represent properly some details such as the non-conservative nature of transport coefficients and the anisotropy of diffusion. Application of approximate theories and representations of cross sections are also discussed.     

Compact three-dimensional camera for robot and vehicle guidance

A very compact 3-D range sensor for robot and vehicle guidance is described. A dual aperture mask in a camera lens is used to transform a small commercially available CCD video camera into a ranging sensor. An active system using a projected laser beam provides a 360° range map which can be used to plan trajectories, either for robots or autonomous vehicles. Good quality panoramic intensity and 3-D images were obtained. Accuracy, speed of acquisition, and cost are discussed. Experimental results are presented.     

Addressing conflicts of interest in nanotechnology oversight: lessons learned from drug and pesticide safety testing

Financial conflicts of interest raise significant challenges for those working to develop an effective, transparent, and trustworthy oversight system for assessing and managing the potential human health and ecological hazards of nanotechnology. A recent paper in this journal by Ramachandran et al., J Nanopart Res, 13:1345–1371 (2011) proposed a two-pronged approach for addressing conflicts of interest: (1) developing standardized protocols and procedures to guide safety testing; and (2) vetting safety data under a coordinating agency. Based on past experiences with standardized test guidelines developed by the international Organization for Economic Cooperation and Development (OECD) and implemented by national regulatory agencies such as the U.S. Environmental Protection Agency (EPA) and Food and Drug Administration (FDA), we argue that this approach still runs the risk of allowing conflicts of interest to influence toxicity tests, and it has the potential to commit regulatory agencies to outdated procedures. We suggest an alternative approach that further distances the design and interpretation of safety studies from those funding the research. In case the two-pronged approach is regarded as a more politically feasible solution, we also suggest three lessons for implementing this strategy in a more dynamic and effective manner.     

Positronics and nanotechnologies: Possibilities of studying nanoobjects in materials and nanomaterials by the method of positron-annihilation spectroscopy

The method of positron-annihilation spectroscopy is shown to be one of the most efficient methods for determining sizes of nanoobjects (vacancies, vacancy clusters); free volumes of pores, cavities, and hollows; and their concentrations and chemical composition at the point of annihilation in porous systems and some defective materials (and generally in a lot of technologically important materials and nanomaterials). Experimental investigations of nanodefects in porous silicon, silicon, and quartz single crystals irradiated with protons and in quartz powders are briefly reviewed.     

Sonoelectrochemistry for energy and environmental applications

Sonoelectrochemistry is the study of the effects and applications of ultrasonic waves on electrochemical processes. The integration of ultrasound and electrochemistry offers many advantages: fast reaction rates, enhanced surface activation, and increased mass transport at an electrode. Significant progress has been made in advancing basic and applied aspects of sonoelectrochemical techniques, which are herein reviewed by addressing the development and applications of sonoelectrochemical processes in energy and environmental areas. This review examines the experimental procedures that are used in various sonoelectrochemical techniques generally used for the synthesis of energy related materials (e.g., fuel cell electrocatalysts and materials for hydrogen production) and for the degradation of various organic compounds/pollutants. The challenges that remain for the sonoelectrochemical production of energy materials, the degradation of organic pollutants, and their associated reaction pathway mechanism(s) are also discussed. This review also highlights the significant improvements made to date. The provided information in this review may be helpful to scientists working in the research areas of environmental remediation, energy exploitation and exploration, as well as synthetic process-oriented research.     

New version of the small-angle x-ray equipment for studying biological structures at the station DICSI in the Kurchatov center of synchrotron radiation and nanotechnologies

The results of modernization implemented at the DICSI x-ray small-angle station (the Kurchatov Center of Synchrotron Radiation and Nanotechnologies) are presented. Certain parameters of the hardware and software environment have been successfully tested using the operating channel of the VEPP-3 storage ring (the Siberian Center of Synchrotron Radiation), where the time-resolved diffractometry (“diffraction cinema”) technique was used to study the dynamic and static behavior of living biological structures in different modes of data accumulation. The circuit designs and the basic parameters of x-ray optical schemes are justified theoretically. The results of test experiments with biological samples are presented.     

Refractive and reflective behavior of polymer prisms used for surface plasmon guidance

Two-dimensional optics with surface plasmons was realized by the use of topographically structured dielectric polymer coatings. Triangles of polymethylmetacrylate (PMMA) with lateral dimensions of some tens of micrometers on top of a silver layer act as two-dimensional prisms for surface plasmons. Refraction and internal reflection of plasmons were investigated by scanning near-field optical microscopy. The change in propagation direction can be explained by Snell's law when taking an effective refractive index for plasmons into account. Furthermore, intensity modulations in the PMMA elements and in the transmitted plasmon beam were observed.     

大学物理实验教学辅导系统的开发设计

为了满足开放式实验的需求,采用Flash开发了物理实验仪器库,根据大学物理实验教学流程,分别采用Excel和Flash嵌入Visual Basic的方式,开发了实验教学辅导系统.该系统既能够实现实验讲解、实验演示和成绩管理功能,又可以根据指定实验和设计实验的模式,以已开发的仪器库为核心,实现指定实验和设计实验的仿真、数据处理;将实验报告分成不变部分和可变部分,主观部分由教师评阅,客观部分由计算机自动评阅.     

ME MS的光学检测方法和仪器

随着微电子机械系统(MEMS,MicroElectroMechanicalSystem)研究的深入和产业化的需求,其检测在MEMS中的重要性越来越大。光学检测方法以其非接触、快速、高精度等优点得到了大量的应用。分析和介绍了国内外采用光学检测法进行MEMS检测的方法及相关检测仪器在测量中的应用。尤其是Nanosurf测量仪器,它是一种独立的三维非接触测量系统,扫描共焦显微镜是基于白光共焦技术,强大且友好的软件控制使所需获得的数据不仅速度快,而且精度很高,并且提供了多种不同的表面分析方法。     

Ultrasonic testing for hydrogen for titanium-based materials and articles

The propagation of ultrasonic (US) waves in hydrogen-saturated alloy based on VT1-0 titanium is investigated. Two characteristic domains of the effect of hydrogen on velocity V _R of US waves are established. A characteristic peak observed on the dependence of the velocity of US waves on the hydrogen concentration makes it possible to determine the hydrogen concentration in titanium at which hydrogen embrittlement begins.