Moving forward responsibly: Oversight for the nanotechnology-biology interface

Challenges and opportunities for appropriate oversight of nanotechnology applied to or derived from biological systems (nano-bio interface) were discussed in a public workshop and dialog hosted by the Center for Science, Technology, and Public Policy of the University of Minnesota on September 15, 2005. This paper discusses the themes that emerged from the workshop, including the importance of analyzing potential gaps in current regulatory systems; deciding upon the general approach taken toward regulation; employing non-regulatory mechanisms for governance; making risk and other studies transparent and available to the public; bolstering mechanisms for public participation in risk analysis; creating more opportunities for meaningful discussion of the social and ethical dimensions of the nano-bio interface; increasing funds for implications and problem-solving research in this area; and having independent and reliable sources for communication. The workshop was successful in identifying ways of moving forward responsibly so that ultimately nanotechnology and its products can succeed in developers’, researchers’, regulators’, and the public’s eyes.     

Protecting workers and the environment: An environmental NGO’s perspective on nanotechnology

Nanotechnology, the design and manipulation of materials at the atomic scale, may well revolutionize many of the ways our society manufactures products, produces energy, and treats diseases. New materials based on nanotechnology are already reaching the market in a wide variety of consumer products. Some of the observed properties of nanomaterials call into question the adequacy of current methods for determining hazard and exposure and for controlling resulting risks. Given the limitations of existing regulatory tools and policies, we believe two distinct kinds of initiatives are needed: first, a major increase in the federal investment in nanomaterial risk research; second, rapid development and implementation of voluntary standards of care pending development of adequate regulatory safeguards in the longer term. Several voluntary programs are currently at various stages of evolution, though the eventual outputs of each of these are still far from clear. Ultimately, effective regulatory safeguards are necessary to provide a level playing field for industry while adequately protecting human health and the environment. This paper reviews the existing toxicological literature on nanomaterials, outlines and analyzes the current regulatory framework, and provides our recommendations, as an environmental non-profit organization, for safe nanotechnology development.     

The emergence and policy implications of converging new technologies integrated from the nanoscale

Science based on the unified concepts on matter at the nanoscale provides a new foundation for knowledge creation, innovation, and technology integration. Convergent new technologies refers to the synergistic combination of nanotechnology, biotechnology, information technology and cognitive sciences (NBIC), each of which is currently progressing at a rapid rate, experiencing qualitative advancements, and interacting with the more established fields such as mathematics and environmental technologies (Roco & Bainbridge, 2002). It is expected that converging technologies will bring about tremendous improvements in transforming tools, new products and services, enable human personal abilities and social achievements, and reshape societal relationships.After a brief overview of the general implications of converging new technologies, this paper focuses on its effects on R&D policies and business models as part of changing societal relationships. These R&D policies will have implications on investments in research and industry, with the main goal of taking advantage of the transformative development of NBIC. Introduction of converging technologies must be done with respect of immediate concerns (privacy, toxicity of new materials, etc.) and longer-term concerns including human integrity, dignity and welfare. The efficient introduction and development of converging new technologies will require new organizations and business models, as well as solutions for preparing the economy, such as multifunctional research facilities, integrative technology platforms, and global risk governance.(*) This is an extension of the presentation made at the Converging Technologies Conference, February 26, 2004, New York.This revised version was published online in August 2005 with a corrected issue number.     

Nanotechnology and occupational health: New technologies – new challenges

An overview of the special issue of the Journal of Nanoparticle Research on nanotechnology and occupational health is presented.     

Emerging methods and tools for environmental risk assessment, decision-making, and policy for nanomaterials: summary of NATO Advanced Research Workshop

Nanomaterials and their associated technologies hold promising opportunities for the development of new materials and applications in a wide variety of disciplines, including medicine, environmental remediation, waste treatment, and energy conservation. However, current information regarding the environmental effects and health risks associated with nanomaterials is limited and sometimes contradictory. This article summarizes the conclusions of a 2008 NATO workshop designed to evaluate the wide-scale implications (e.g., benefits, risks, and costs) of the use of nanomaterials on human health and the environment. A unique feature of this workshop was its interdisciplinary nature and focus on the practical needs of policy decision makers. Workshop presentations and discussion panels were structured along four main themes: technology and benefits, human health risk, environmental risk, and policy implications. Four corresponding working groups (WGs) were formed to develop detailed summaries of the state-of-the-science in their respective areas and to discuss emerging gaps and research needs. The WGs identified gaps between the rapid advances in the types and applications of nanomaterials and the slower pace of human health and environmental risk science, along with strategies to reduce the uncertainties associated with calculating these risks.     

Radioactivity concentration measurement and analysis in construction floor materials of Korea

In this study, the radioactive concentrations contained in samples of commonly used building floor materials were measured. This result can be used as basic information for public health and the environment. Among building floor materials, samples of induction blocks, cement bricks, artificial granite blocks and compact high-pressure blocks were chosen and used. A detailed gamma nuclide analysis was performed with a multichannel analyzer by putting these samples on a high-purity germanium detector which is a semiconductor detector. In order to measure the concentration of radionuclides, a spectrum file was obtained by analyzing the concentration of gamma radionuclides and setting the measurement time as 1000, 4000, 7000 and 10,000?s. According to the study results, K-40, Bi-214, Pb-214, Ra-226 and U-235 were detected in the induction blocks measured at 10,000?s and K-40, Th-230, Bi-214, Pb-214, Ra-226 and Na-22 were detected in the cement bricks measured at 10,000?s. K-40, Bi-214, Pb-214, Th-234, U-235 and Ra-223 were detected in the artificial granite blocks measured at 10,000?s and K-40, Bi-214, Pb-214, Th-234, Ra-226, Ra-223 and Mn-54 were detected in the compact high-pressure blocks. In conclusion, low-level radioactivity was detected in building floor materials, so it is thought that measures to reduce radioactivity and further studies on this will be needed.     

An original approach for Raman spectroscopy analysis of radioactive materials and its application to americium‐containing samples

An approach for Raman measurements of highly radioactive samples is presented here. The innovative part of this approach lies in the fact that no single part of the Raman equipment is in direct contact with the radioactive sample, as the sample is sealed in an alpha‐tight capsule. Raman analysis is effectively performed through the optical‐grade quartz window closing the capsule. This allows performing micro‐Raman measurements on radioactive samples with no limitations on the laser source wavelength, polarisation mode, spectrometer mode and microscope mode (provided the focal length of the microscope objective is greater than the thickness of the quartz window and with sub mg samples). Some example results are shown and discussed. In particular, some spectral features of americium‐containing oxide nuclear fuel specimens are presented. Raman spectra clearly reveal in these specimens the presence of abundant oxygen defects induced in the fcc fluorite lattice by trivalent americium. In order to complete the analysis the Raman spectrum of pure americium dioxide was also measured with a lower energy excitation source compared with previous research. The current results seem to be consistent with the possible occurrence of a photolysis process induced by the Raman laser, resulting in the formation of hyperstoichiometric americium sesquioxide Am₂O_{3 + z}. Such a photolytic process is deemed to be unavoidable when visible lasers are used as excitation sources for the Raman analysis of americium dioxide. © 2015 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons, Ltd.     

Automated interferometric technique for express analysis of the refractive indices in isotropic and anisotropic optical materials

This paper deals with the technique for the refractive index measurements based on the interferometry of a rotated parallel plate (IRPP). The device consists of the Michelson interferometer, the sample rotation system and the optoelectronic registration system. A refractive index of parallel plates is determined by their rotation through measuring simultaneously a shift of interference fringes. Although the IRPP technique is known from long ago [Shumate MS. Appl Opt 1966;5:327] several considerable improvements have been done in order to improve the accuracy of the method. The measuring process is completely automated. The method has been tested on the model crystals of the lithium niobate giving the magnitudes for ordinary and extraordinary refractive indices as n₀=2.2865±0.0007 and n_e=2.2034±0.0007. A considerable increase of accuracy is reached in our case by an automation of the measuring procedure, development of a new software as well as implementing the interferometric method for a precise determination of a sample zero position. The automated refractometer is offered for use in research laboratories and industry.     

An experimental study of impact-induced failure events in homogeneous layered materials using dynamic photoelasticity and high-speed photography

The generation and the subsequent evolution of dynamic failure events in homogeneous layered materials that occur within microseconds after impact were investigated experimentally. Tested configurations include three-layer and two-layer, bonded Homalite specimens featuring different bonding strengths. High-speed photography and dynamic photoelasticity were utilized to study the nature, sequence and interaction of failure modes. A series of complex failure modes was observed. In most cases, and at the early stages of the impact event, intra-layer failure (or bulk matrix failure) appeared in the form of cracks radiating from the impact point. These cracks were opening-dominated and their speeds were less than the crack branching speed of the Homalite. Subsequent crack branching in several forms was also observed. Mixed-mode inter-layer cracking (or interfacial debonding) was initiated when the intra-layer cracks approached the interface with a large incident angle. The dynamic interaction between inter-layer crack formation and intra-layer crack growth (or the so-called “Cook–Gordon Mechanism”) was visualized for the first time. Interfacial bonding played a significant role in impact damage spreading. Cracks arrested at weak bonds and the stress wave intensity was reduced dramatically by the use of a thin but ductile adhesive layer.     

The density of helium in bubbles in implanted materials: Theoretical interpretation of VUV absorption and EELS spectroscopy

The shape of the He resonance absorption line of He bubbles in metals is discussed in terms of He-metal and He-He interactions. For bubble radii larger than 10 Å the metal matrix effects are found to be negligible. For small vacancy clusters there is as yet no quantitative calculation of the role of the metal conduction electrons in determining the position and width of the He resonance excitation.

The He-He interactions are treated within static line broadening theory which assumes pairwise additivity of the interactions. These are taken from ab initio quantum mechanical calculations of 2p excimer potential energy curves due to Guberman and Goddard and to Gupta and Matsen. The radial pair distribution function required by our statistical line shape calculation is computed from two theoretical models of the dense fluid: either the exact solution of Percus-Yevick's equation for hard spheres or a Molecular Dynamics computer simulation based on an accurate pair potential. The two approaches give very similar results. The blue shift of the resonance line is found to depend nearly linearly on density but our value for the slope differs substantially from the prediction of a model band structure calculation performed by the Jülich group in the framework of density functional theory.     

Multivariate analysis of combined Raman and fibre‐optic reflectance spectra for the identification of binder materials in simulated medieval paints

The non‐invasive identification of paint materials used in works of art is essential, both for preserving and restoring them, and also for understanding and verifying the history surrounding their creation. As such, the development of suitable non‐invasive techniques has received much interest in recent years. We have investigated the use of Fourier transform (FT)‐Raman spectroscopy and fibre‐optic reflectance spectroscopy (FORS), together with multivariate principal‐component analysis (PCA) techniques, in order to identify the pigment and binding materials used in made‐up samples representative of real artwork. We demonstrate that both types of spectroscopy provide complementary information which can be used to identify the pigments and binders in paint samples. We show that PCA with FT‐Raman spectra can be used to assist in the identification of oil‐based binders, and that the additional data provided by FORS spectra enables PCA on combined spectra to identify more complex proteinaceious and polysaccharide‐based binding media. The results presented here demonstrate that multivariate analyses of lead‐based paints, using data measured by FT‐Raman and FORS in conjunction, have much potential for identifying individual pigments and binders in paint samples. This provides a path towards computer‐assisted characterisation of paint materials on artwork. Copyright © 2013 John Wiley & Sons, Ltd.     

微波吸收法研究Mn,Cu掺杂对ZnS:Mn,Cu光生载流子复合过程的影响

采用微波吸收法，测量了ZnS:Mn,Cu粉末材料受到超短脉冲激光激发后，其光生电子和浅束缚态电子的衰减过程.发现Mn,Cu的浓度对导带电子的寿命有明显的影响，提高掺杂浓度会使光生电子的寿命大大缩短，还研究了掺杂浓度对光致发光强度的影响. 关键词： 发光材料 硫化锌 光电子 微波吸收技术     

Silane-modified polymers as interphases in glass-fibre-reinforced composites: 2. Grafting and crosslinking of interphase materials

_—This paper presents an interphase engineering technique suitable for grafting silane-modified polymers onto glass fibres to be used in composites with enhanced impact tolerance. The silane-modified polymers include ethylene polymers grafted with γ-methacryloxypropyltrimethoxysilane (MPS) and a copolymer of butyl acrylate (BuA) and MPS. The grafting of functionalized interphase materials onto glass fibres is performed in solution. By changing the concentrations of the solutions, different amounts of polymer can be deposited on the fibres. Water crosslinking of the polymer gives the possibility of producing stabilised interfacial polymer coatings over a range of thicknesses. It is concluded that acidic conditions (1) promote the grafting of silane-modified polymers on glass fibres and (2) for a given reaction time, increase the amount of crosslinked polymer in the interphase, i.e. yield more stable interphases. It is also likely that preserving acidic conditions at the fibre/polymer interface is important for maintaining bonding across the interface. It is shown that polystyrene/glass-fibre composites having SEBS at the interface are promising candidates for high-impact-tolerance composites.     

Process Analytical Chemistry: Applications of Near Infrared Spectrometry in Environmental and Food Analysis: An Overview

Abstract

This review provides a valuable source of information on the technological advances in near infrared absorption spectrometry area and its industrial applications, especially on the alimentary technology and environmental applications over biofuels.     

Challenges and opportunities in quantitative analyses of lead,cadmium, and hexavalent chromium in plant materials by laser-induced breakdown spectroscopy: A review

Bearing the merits of rapid, minimally destructive, and simultaneous multi-element analyses, laser-induced breakdown spectroscopy (LIBS) shows its unique advantages in quantitative analyses of lead, cadmium, and hexavalent chromium in plant materials. However, the greatest challenge LIBS must confront is calibration. Various methods for calibration are proposed and put into effect; nevertheless, limits of detection acquired by LIBS are not acceptable when they are compared with the maximum residue limits drawn up by governments, and LIBS's performances in quantitative analyses are to be improved. This review summarizes recent studies of analyzing lead, cadmium, and hexavalent chromium in plant materials quantitatively by LIBS; weighs the strengths and weaknesses of their calibration methods; and recommends the combination of matrix-matched standards based on spiked sample materials and internal standard as well as chemometrics in complicated situations for calibration in LIBS. Selecting the emission line of the analyte, sample enrichment and signal enhancement are measures that this review puts forward to improve the performances of LIBS in calibration. These quantitative analyses of lead, cadmium, and hexavalent chromium in plant materials by LIBS provide an opportunity to be utilized in mapping distributions and remediation for soil and water, as well as supervision for agricultural products safety and pollution treatments.     

The sp2 and sp3 fractions of unknown carbon materials: electron energy-loss near-edge structure analysis of C-K spectra acquired under the magic-angle condition by the electron nanobeam technique

A method is described for the quantification of the sp², sp³ and intermediate hybridizations in several carbon (C) material samples. Electron energy-loss near-edge spectra were acquired using fast electrons (120 keV) in an electron microscope in nanobeam configuration under the so-called ”magic-angle” condition, and were analysed to extract the sp² and sp³ fractions, and identify the possible mixed sp^2+ε hybridizations. The method consists in projecting the unknown spectra on a basis made up of pure sp² and sp³ spectra, obtained under the same experimental conditions from graphite and diamond crystals, respectively. The residual spectra contain information about the intermediate hybridizations sp^2+ε occurring in the samples. The method was successfully tested on “ab initio” numerically generated spectra relative to amorphous C materials. Finally, it was applied to actual C amorphous and pyrolytic samples, and results were compared to those obtained by the most commonly used, conventional ”three-Gaussian” method. The combined application of electron diffraction and spectroscopy, in the nanobeam configuration, yielded useful information about the atomic and electronic structure from very small volumes of the unknown C material.     

An atypical coordination in hexacyanometallates: Structure and properties of hexagonal zinc phases

In hexacyanometallates, the involved transition metals are usually found with octahedral coordination. The exception corresponds to the hexagonal zinc phases where this metal appears tetrahedrally coordinated to N ends from the CN ligands. Those zinc hexacyanometallates where such atypical coordination appears were identified and for four of them the crystal structure was refined from X-ray diffraction powder patterns using the Rietveld method. Zinc hexacyanoferrates (III), hexacyanocobaltate (III), hexacyanoiridate (III) and the mixed zinc-cesium hexacyanoferrate (II) were found to be dimorphic, cubic (Fm-3m) and hexagonal (R-3c), related to the zinc atom in octahedral or tetrahedral coordination, respectively. In the absence of an exchangeable cation, the hexagonal phases result anhydrous. This last feature was attributed to a low polar character for the pores surface. The Mössbauer spectrum of hexagonal zinc hexacyanoferrate (III) is an unresolved quadrupole splitting doublet (Δ=0.18 mm/s). The iron nucleus is sensing a weak electric field gradient related to a relatively high symmetry for its ligands and charge environment. The IR spectrum appears to be an excellent sensor to identify the coordination for the zinc atom in a given sample. For the tetrahedral coordination, the CN stretching absorption was found at least 8 cm⁻¹ above the frequency observed for this vibration in the octahedral one. For hydrated phases, the crystal water evolves on heating preserving the material porous framework. The temperature at which the material becomes anhydrous parallels the polarizing power of the charge balancing cation sited within the channels. Hexagonal Zn-Cs ferrocyanide becomes anhydrous at 100 °C, while for the Zn-Na analogue a heating close to 200 °C is required. The stability temperature range for the anhydrous phases depends on the nature of the engaged hexacyanometallate anion; the higher stability was observed for hexacyanoferrates (II). Zinc ferricyanide shows the weaker magnetic interaction for the hexagonal modification due to an unfavourable geometry for the overlapping path between the unpaired electrons on the iron(III) atoms. The open 3D porous network is formed by relatively large ellipsoidal cavities, three per cell, communicated through elliptical openings (windows), six per cavity. For dimorphic zinc hexacyanometallates (III), the most compact structure (higher density) corresponds to the hexagonal modification, however, it has the largest cavity windows and cavity (pore) size, and also the higher thermal stability.     

Electrostatic potential and interaction energies of molecular entities occluded in the AlPO4-15 molecular sieve: determination from X-ray charge density analysis

Electrostatic interaction energies of water molecules, hydroxyl and ammonium ions occluded in AlPO₄-15 molecular sieve are estimated from the modeling of the experimental X-ray charge density by numerical integration using a partitioning of the density based on multipolar pseudo-atoms.     

Surface of Zn-Mn-O and its role in room temperature ferromagnetism: An XPS analysis

The existence of ferromagnetism in Zn-Mn-O semiconductor samples and dependence on the preparation condition were investigated. We systematically examined the samples with manganese concentration ranging from 0 to 10 at.%, prepared by a solid state reaction route using (ZnC₂O₄·2H₂O)_1−x and (MnC₂O₄·2H₂O)_x as precursors. Thermal treatment was carried out in air at temperatures ranging from 400 to 900 °C. The samples were investigated by X-ray diffraction, transmission electron microscopy, magnetization measurements and XPS spectroscopy. XPS surface composition, chemical analysis and depth profiling were successfully employed on powder revealing the chemical composition at the surface of the grains and underneath. The present investigation suggests that physical properties and observed room temperature ferromagnetism might be due to grain surface effects. It seems that the ferromagnetic phase is correlated with oxygen build up at the surface.     

Burning characteristics of candle flames in sub-atmospheric pressures: An experimental study and scaling analysis

Burning characteristics (mass burning rate, natural convection boundary layer thickness, flame height and dark zone height) of laminar diffusion flames produced by a candle at sub-atmospheric pressures in the range of P_∞?=?50–100?kPa were experimentally studied in a reduced-pressure chamber; such data are not reported to date. Scaling analysis was performed to interpret the pressure dependence. The new experimental findings for candle flames in the sub-atmospheric pressures were well interpreted by the proposed scaling laws: (1) the mass burning rate was higher for a candle with larger wick length, and it increased with increasing ambient pressure, a stagnant layer B-number model based on natural convection boundary (flame boundary layer thickness) was developed to scale the mass burning rate of candle flames at various pressures; (2) the flame boundary layer thickness was wider in lower pressure and can be well represented by a natural convection boundary layer solution; (3) flame height was higher for a candle with larger wick length, meanwhile the ratio of flame height to burning rate was independent of pressure; (4) the flame dark zone height representing a soot formation length scale changes little with pressure, meanwhile its ratio to the total flame height is scaled with pressure by $P_{\infty }^{?1/2}/L_{w,e}^{3/4}$ (L_w,e is effective wick length inside flame). This work provided new experimental data and scaling laws of candle flame behaviors in sub-atmospheric pressures, which provided information for future characterization and soot modeling for diffusion flames associated with melting and evaporation processes of solid fuels.