California NanoSystems Institute
CNSI
Text Size: A A A A

December 02, 2010

Su-Jung (Candace) Tsai, Sc.D.
Manager of Environmental Health and Safety at the Center for High-rate Nanomanufacturing (CHN)
University of Massachusetts Lowell
Occupational and Environmental Health and Safety for Nanotechnology: Setting the Pace for the Next Phase
Abstract: With nanotechnology moving from development to commercialization at a more rapid rate, so too are calls for a more comprehensive understanding of the environmental and occupational health risks associated with various nanomanufacturing processes. There are indications that a range of engineered nanomaterials, including nanoparticles, agglomerates of nanoparticles, and particles of nanostructured materials, are likely to present potential risks to human health and the environment. Possible negative properties of these materials include their ability to penetrate dermal barriers, cross cell membranes, travel neuronal pathways, breach the gas exchange regions of the lung, travel from the lung throughout the body, and interact at the molecular level. In particular, critical reviews on the toxicity of carbon nanotubes (CNTs) give credence to research that indicates damage to lung tissue in mice.

We have the opportunity to address occupational and environmental health and safety issues in a sustainable manner from the beginning. It is extremely important that all researchers and manufacturers working with engineered nanoparticles incorporate sustainable practices into their work. This talk will review the current knowledge about occupational and environmental exposures to engineered nanoparticles and techniques for evaluating and controlling such exposures. Case studies from our research will be discussed. In addition, the current consensus on best practices for working with engineered nanoparticles and the challenges presented by the next phase will be presented and discussed.

Bio: Dr. Su-Jung (Candace) Tsai is a Manager of Environmental Health and Safety at the Center for High-rate Nanomanufacturing (CHN) and a researcher in the Department of Work Environment at the University of Massachusetts Lowell. She received both her BS and MS in chemical engineering, and worked as a senior engineer at a petrochemical company for several years in Taiwan. At UMass Lowell she received her MS in management science and her Doctorate in Occupational Hygiene and Cleaner Production. Dr. Tsai has performed ground-breaking research to evaluate and control occupational exposures to engineered nanoparticles, and received the Department?s Scholarship Award for her doctoral research. Led by Dr. Tsai, the EHS research group at CHN has been in the forefront of nanoparticle EHS research including occupational and environmental exposures, the best practices to be followed and engineering control strategies to minimize the exposure. Her publications including the performance of laboratory fume hoods when handling nanopowders and the twin screw extrusion of nanocomposites are the first such papers in the peer-reviewed literature. She was awarded the best paper presented at the American Industrial Hygiene Conference by the AIHA Lab Health and Safety Committee. She and Dr. Michael Ellenbecker are writing a new textbook titled ?Health and Safety Considerations for Working with Engineered Nanoparticles in Industry?. Dr. Tsai recently led the establishment of a partnership between CHN and NIOSH as joint force to strengthen the move. She is co chairing the 5th Symposium on Nanotechnology, Occupational and Environmental Health in August 2011.

November 09, 2010

Berry Jonker
Senior Scientist and Head of the Magnetoelectronic Materials & Devices section in the Materials Science & Technology Division Naval Research Laboratory, Washington, DC
Silicon Spintronics
Abstract: We describe a simple and efficient way to electrically inject spin-polarized electrons from Fe/Al2O3 and Fe/SiO2 tunnel barrier contacts into silicon, achieving a majority electron spin polarization of at least 30%. Initial measurements utilized optical detection of the circularly polarized electroluminescence resulting from radiative recombination of the spin-polarized electrons injected from a ferromagnetic metal contact [1]. Recent theoretical work provides a more quantitative interpretation of the EL polarization [2], confirming an electron spin polarization of 30%. These spin injecting contacts are utilized in a lateral transport geometry, where we generate both spin-polarized charge currents and pure spin diffusion currents using a non-local spin valve (NLSV) structure. We demonstrate that we can manipulate and electrically detect the polarization of the pure spin current [3,4] as required for information processing. This pure spin current produces a net spin polarization and an imbalance in the spin-dependent electrochemical potential, which is detected as a voltage by a second magnetic contact outside of the charge flow path. The spin polarization is determined by both the magnetization/bias of the injector contact and spin precession induced by a magnetic field applied normal to the surface (Hanle effect). The Hanle measurements yield spin lifetimes ~ 1ns at 10K for lateral transport in n-doped Si (~ 4x1018 cm-3) [3]. Similar measurements probe the spin accumulation directly under the injecting contact. We observe Hanle precession of electron spin accumulation in Si for a wide range of bias conditions, show that the magnitude of the Hanle signal is in good agreement with theory, and that the spin lifetime varies with the Si carrier density. These results confirm spin accumulation in the Si transport channel well above 300K rather than trapping in localized interface states, and enable utilization of the spin variable in practical device applications.

References: [1] B.T. Jonker et al, Nature Phys. 3, 542 (2007); C. Li et al, APL 95, 172102 (2009); G. Kioseoglou et al, APL 94, 122106 (2009).
[2] P. Li and H. Dery, arXiv:1003.1709v2, accepted Phys. Rev. Lett.
[3] O.M.J. van t? Erve et al, APL 91, 212109 (2007).
[4] O.M.J. van t? Erve et al, IEEE Trans. Elec. Devices 56 (10), 2343 (2009).

November 01, 2010

Wojtek Wlodarski
School of Electrical and Computer Engineering
Royal Melbourne Institute of Technology
Nanomaterial Based Optical Gas and Vapour Sensors: The First 5 years
Abstract:The application of nanomaterials in the field of optical gas sensing has become recently a new growing area of interest. Nanomaterials could be combined with different optical transducing platforms such as: spectrophotometers, waveguides, including fibers, planar and chanel waveguides as well as based on plasmon resonance technique. The research in this area is mainly focused on the changes of absorbance, refractive index, photoluminescene and chemiluminescence intensity. Combining optical transducers with nanostructured materials such as semiconducting metal oxides (SMO), conductive polymers (CP), SMO/CP composites and carbon nanotubes results in the development of novel gas and vapour sensors with several advantages which will be discussed. Numerous recently developed gas and vapour sensors for: O2, O3, NO, NO2, CO, CO2, H2, NH3, C3H6, VOC and H2O will be presented.
October 12, 2010

Paul Schulte
The National Institute for Occupational Safety & Health (NIOSH)


Streaming Video

Nanotechnologies and Nanomaterials in the Occupational Setting
Workers are generally the first people in society to be exposed to the hazards of an emerging technology and nanotechnology is no exception. The workplaces where nanomaterials are developed, investigated, manufactured, used, and disposed of are quite varied and they span all economic sectors. To protect the health and safety of workers in all of these workplaces requires a concerted effort that includes: hazard identification, exposure assessment, risk characterization, and risk management. In this presentation, the current status of efforts in each of these categories will be discussed. Although there are more than 1,000 "nano-enabled" products in commerce, there is virtually no human evidence of adverse health effects attributed directly to engineered nanoparticles, in part, due to the current observations that exposures may be limited and short. Nonetheless, there is a coalescing body of evidence from animal and in vitro studies that indicates that various types of nanomaterials may be hazardous to workers. However, there are also limited published data on exposure and practically no comprehensive and quantitative exposure assessments. There have been few formal risk assessments published and no occupational exposure limits (OELs) specifically for engineered nanoparticles have been officially promulgated, although several exposure guidelines have been published by nanomaterial producing companies. A precautionary approach to risk management has been strongly advocated by various health authorities internationally and there is an array of useful general risk management guidance, but guidance for many specific operations, engineering controls, and medical surveillance is lacking. In addition to further hazard and control research, the next major phase in the efforts to protect workers as nanomaterials become more widely available in commerce is to focus on assessing barriers that prevent implementation of precautionary guidance and to identify and evaluate worker populations.