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Framework for new report by a committee of the National Research Council for the National Academies. Credit: NRC.

Nano environmental health and safety is clearly an important topic and one that is frequently referenced at materials conferences I have attended. But despite all the balloon juice, it seems to me that work over the last few years on research, documentation and development of databases on the safety and health of various nanomaterials hasn’t gone very far.

Good people at NIST, NIH and other institutions have been working for at least five year on trying to get some momentum going, and I do get that the nano EHS work is complicated (and that there yet seems to be even a common language among various researchers and between the research and industry communities) and expensive, but unfortunately, it feels like there is little substantial progress being made.

I think the National Academies agrees:

The committee that wrote the [a new report from the National Research Council] found that over the last seven years there has been considerable effort internationally to identify research needs for the development and safe use of nanotechnology, including those of the National Nanotechnology Initiative, which coordinates US federal investments in nanoscale research and development. However, there has not been sufficient linkage between research and research findings and the creation of strategies to prevent and manage any risks. For instance, little progress has been made on the effects of ingested nanomaterials on human health and other potential health and environmental effects of complex nanomaterials that are expected to enter the market over the next decade. Therefore, there is the need for a research strategy that is independent of any one stakeholder group, has human and environmental health as its primary focus, builds on past efforts, and is flexible in anticipating and adjusting to emerging challenges, the committee said.

The committee recommends four research categories “which should be addressed within five years:”

• Identify and quantify the nanomaterials being released and the populations and environments being exposed;
• Understand processes that affect both potential hazards and exposure;
• Examine nanomaterial interactions in complex systems ranging from subcellular to ecosystems; and
• Support an adaptive research and knowledge infrastructure for accelerating progress and providing rapid feedback to advance research.

Will Washington fund such efforts? It’s hard to know given the political environment, and the NRC warns, “[A]ny reduction in the current funding level of approximately $120 million per year over the next five years for health and environmental risk research by federal agencies would be a setback to nanomaterials risk research.”

NRC also says other public, private and global resources will be needed in the areas of “informatics, nanomaterial characterization, benchmarking nanomaterials, characterization of sources and development of networks for supporting collaborative research.”

I haven’t had a chance to read the 200+ page report, but the summary seems to contain a fairly thorough strategy, with one exception: It’s not very helpful in suggesting how to implement the strategy, which always has seemed to me to be the weakness in these discussions. Someone logically has to be given the power and resources to wrangle all of the stakeholders.

What about the NNI? Can it spearhead the effort? The committee astutely puts the kybosh on that notion, at least with the current configuration of NNI agencies:

The committee said that the current structure of the NNI — which has only coordinating functions across federal agencies and no top-down budgetary or management authority to direct nanotechnology-related environmental, health, and safety research — hinders its accountability for effective implementation. In addition, there is concern that dual and potentially conflicting roles of the NNI, such as developing and promoting nanotechnology while identifying and mitigating risks that arise from its use, impede application and evaluation of health and environmental risk research. To carry out the research strategy effectively, a clear separation of management and budgetary authority and accountability between promoting nanotechnology and assessing potential environmental and safety risks is essential.

Its not clear to me if the NRC/NAS has an alternative to the NNI leadership in mind, or just a restructuring of NNI, but the committee says whatever group is in charge will require “sufficient management and budgetary authority to direct development and implementation of a federal EHS strategy across NNI agencies and to ensure integration of federally supported EHS research with research undertaken by the private sector, the academic community and international organizations.” In other words, the dual NNI responsibilities of simultaneously promoting nanomaterials and assessing their EHS effects generates lots of conflicts and therefore accountability for the two should be clearly separated.

Addendum from Eileen: The Danish have taken a first stab at addressing exactly this issue, according to a press release published today. The Danish Environmental Protection Agency, the Technical University of Denmark and the National Research Centre for the Working Environment collaborated on developing a database concept for cataloging and evaluating the risks associated with nanomaterials. The Executive Summary of the report (pdf) explains:

Through this project, DTU Environment and the National Research Centre for the Working Environment have initiated the development of a screening tool, NanoRiskCat (NRC), that is able to identify, categorize and rank expo- sures and effects of nanomaterials used in consumer products based on data available in the peer-reviewed scientific literature and other regulatory relevant sources of information and data. The primary focus was on nanomaterials relevant for professional end-users and consumers as, as well as nanomaterials released into the environment.

They used nanosized TiO₂ (used in sunscreens) and C₆₀ (used in lubricants) as demonstration materials for the database.

To make it easy to evaluate risks quickly, a color coded five-dot system was developed, where the first three dots “refer to potential exposure of professional end-users, consumers and the environment,” and the last two dots “refer to the hazard potential for humans and the environment.”

The color code scheme is the universally recognized red, yellow and green, corresponding to high, medium and low risks. In cases where the risk is unknown, the dot is grey.

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A unique method for processing ZnO nanowires and polythiophenes results in a hybrid structure with nanometer scale ordering and a high crystallinity, showing great promis for the future of hybrid photovoltaics. Credit: Advanced Materials; Wiley.

Inorganic/organic hybrid materials show great promise for use in photovoltaic devices, where the advantages of both types of materials could be combined to better harvest the sun’s energy. For the potential of hybrid materials to be fully realized, it isn’t sufficient simply to select the right materials, but the precise arrangement of these materials at small length scales can also be crucial to determining their ultimate properties and usefulness. Professor Chinedum Osuji and coworkers have developed a unique method for processing ZnO nanowires and polythiophenes that results in a hybrid structure with nanometer-scale ordering and a high crystallinity, showing great promise for the future of hybrid photovoltaics.

In order to understand why ordering is so crucial to the performance of hybrid photovoltaics, it is instructive to look closer at how such devices work. In its most basic form, the function of a photovoltaic device is to convert light energy from the sun into electrical energy (electrons and holes with negative and positive charges respectively) with a high efficiency. The light absorption usually occurs in the organic material, thereby creating an electron-hole pair. In order to extract useful work from the device, the electron must be transferred to the inorganic material, and then the electron and hole can be pulled to opposite sides of the device by the electric field in order to complete the electronic circuit. By ordering the materials at the nanoscale, it can be assured that the charge carriers have only a short distance to travel in order to complete this process. The molecular ordering within the polymer layer is very important where charge transport is much more favorable in a crystalline polymer than an amorphous one. Furthermore, the orientation is also key, where charge transport along polymer chains is more favorable than lateral hopping between chains. By controlling the arrangement of these materials as precisely as possible (and at multiple length scales), the losses from the device can be minimized to achieve a high power conversion efficiency.

Achieving this type of complex ordering at small length scales is not easy. To arrange each of these domains by hand, we would require nano-sized tools, and a macro amount of patience. However, by taking advantage of intermolecular and other long-range forces we can coerce the materials to order themselves. This class of methods is fittingly called “self-assembly.” Professor Osuji and coworkers were able to take advantage of electrostatic forces to graft a thiophene-based polymer onto the surfaces of ZnO nanowires, creating a new crystalline phase that does not exist when the polymer is processed alone. Then, in order to arrange the coated nanowires, a shear force was applied to the hybrid material to achieve the ordering shown in the image above. As an alternative method, the authors also achieved very similar ordering by applying a magnetic field after a small amount of cobalt was incorporated into the nanowires. In both cases, the result was an ordered hybrid material boasting a near-ideal geometric arrangement for charge collection in photovoltaic devices. With creative methods such as these, the future of hybrid materials appears bright, and we may reap the rewards in the next generation of solar cells.

The paper is: 10.1002/adma.201103708 ; DOI: Shanju Zhang et. al., Advanced Materials

John Ulrich is a writer for MaterialsViews.com. This story first appeared in the 1/5/2012 edition.

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Alfa Aesar launches mobile website for easy access to product information

Alfa Aesar, a Johnson Matthey Company, announced the launch of a new mobile website designed specifically for use on smart phones. The site allows users to quickly and easily access Alfa Aesar’s detailed product specifications using mobile platforms. The site has been optimized globally for Nokia, Moto, iPhone, Samsung, Blackberry, Sony and Android devices, and is available in ten languages. The mobile website enables users to access full product specifications for Alfa Aesar’s complete range of chemical compounds, metals and materials. Users can also access certificates of analysis and material safety data sheets for all products, as well as link through to the full site.

Horizontal media mills figure prominently in lithium-ion battery preproduction

With the federal government looking for 1 million electric vehicles on US roadways within just four years, attritor and horizontal media mill manufacturer Union Process Inc., is right in the middle of the mix. Lithium-ion batteries are the focus for powering these vehicles, and the Akron-based equipment maker has developed a two-phase process for grinding and dispersing the phosphate precursor required for the batteries. The first phase utilizes the Union Process S-series attritors to grind and disperse the coarse precursor powder to a 1-3 um particle-size range. The second phase runs through the company’s DMQ series horizontal media mills, dispersing the finished material to a primary particle-size range of 200-300 nm.

Unifrax acquires catalytic converter emission control mat business

Unifrax announced that through its Hong Kong subsidiary, Unifrax Asia-Pacific Holding Ltd, it had acquired the catalytic converter emission control mat business of Zhejiang Bondlye Motor Environmental Technology Co. The Bondlye Mat Business produces support mat products used in automotive catalytic converters. They are the leading supplier of emission control mat products to the domestic Chinese automotive manufacturers.

Virial launches first production line for nanostructured ceramic and cerametallic goods

Ceremonies were held in St. Petersburg today for the first production line for new high-tech goods of nanostructured ceramic and cerametallic materials. The facilities belong to Virial, a project company created with coinvestment from RusNano. The total cost of the new project is 1.7 billion rubles. Investment fund CapMan, a leading fund in direct financing in Scandinavian countries and Russia, and agriculture innovator Siberian Organics have joined RusNano as coinvestors. Virial has set up the entire production cycle for cutting instruments that are suited to hard-to-process materials and slide bearings able to accommodate extreme working conditions, higher pressure, and hotter temperatures. Items will be manufactured using a unique patented technology.

Theramax does pioneering work in solar cooling system

Pune-based Thermax Ltd recently designed and commissioned a unique solar conditioning system at the Solar Energy Centre in Gurgaon, Haryana, India. The 100-kW technology demonstration project was inaugurated by Union Minister for New and Renewable energy Farooq Abdullah in the presence of Union Power Minister Sushilkumar Shinde. In this innovative installation, claimed to be the first-of-its-kind in the world, Thermax has integrated a triple-effect chiller and solar parabolic concentrators (collectors), both indigenously developed by the company.

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A key tenet of the Materials Genome Initiative for Global Competitiveness (pdf) is using computation to reduce the time for materials development by 75%, from 20 years to 5 years. A recent press release from Fujitsu Laboratories in Japan gives an early clue about the feasibility of this approach.

Fujitsu is interested in developing materials for novel nanodevices to replace silicon large scale integration devices. The drive to shrink electronic devices is starting to run up against the physical limits of the material to be miniaturized.

Turning to computational methods, Fujitsu used a first-principles method to calculate the electrical properties of a 1,000-atom device based on carbon nanotubes and graphene electrodes. In the press release the company says the significance of this breakthrough is that “The new technology opens the door to the design of exceptionally high-speed, energy-efficient nanodevices that break totally new ground with their development.”

First-principles computation is based on the quantum mechanics of a material’s electrons and atoms, thus experimental data or empirical parameters are not needed. It is useful for simulating the properties of materials like carbon where small differences in atomic arrangement results in large property differences. Consider, for example, how different the electrical properties of charcoal, graphite and diamond are.

Electrical properties were calculated using software developed by the Japan Advanced Institute for Science and Technology and the computational power of a supercomputer at the Information Technology Center at Nagoya University. First-principles calculations are iterative and tend to need a lot of computing time and memory. Each iteration updates input values and the computation continues until the output values converge. It took about three days to calculate the electrical properties of a 1,000-atom nanodevice using about one-third of the supercomputer’s capacity.

In the press release, Fujitsu explained that they worked with JAIST to tweak the software somewhat, and that they also used a “hybrid parallel processing technique.” As a result, Fujitsu was able to include the modeling of several times more atoms than it had previously be able to do.

The nanodevice modeled is a carbon nanotube with graphene electrodes. Lithium atoms occupied the inner edges of the graphene electrodes and several hydrogen atoms bridge the atomic layer between the electrodes and the nanotube. This is a very simple system, atomically, compared to most commercial engineered materials, which often have complex compositions or atomic structures. However, the company said its success in this instance “significantly paves the way to designing novel nanodevices.”

Because the Materials Genome Initiative is aimed at elevating the United States’ national competitiveness, there is some irony of discussing the efforts of a Japanese enterprise. However, this example illustrates the type of technology—also available in the US—that the MGI intends on leveraging.

And, while Fujitsu’s work shows great promise for designing a type of nanodevice, it also demonstrates that this route to materials design requires sizeable computational investment (hardware and software). Even at the speed attained by Fujitsu, the span of potential materials compositions, crystalline structures, properties and applications make it clear that a lot of computational capacity and agility will be needed in the US.

The Fujitsu work was published in the Aug. 11 online edition of Applied Physics Express.

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Laser-heated diamond anvil cell allows very large hydrostatic pressure to be applied to amorphous carbon aerogels. Cavity dimensions are approximately 100–170 μm wide by 35 μm thick. Credit: LLNL.

While there has been considerable interest in capturing the properties of diamond in a low-density form, converting an amorphous carbon aerogel to a crystalline phase without collapsing the porous network has proven tricky — but not impossible.

In a paper published in the May 9 online edition of the Proceedings of the National Academy of Sciences, a team of Lawrence Livermore researchers describe the successful synthesis of a diamond aerogel from an amorphous carbon aerogel precursor (“Synthesis and characterization of a nanocrystalline diamond aerogel,” doi: 10.1073/pnas.1010600108). The density of the amorphous precursor aerogel in this study is 0.04 g/cm³, which according to a LLNL press release, is about the density of the nanocrystalline diamond aerogel (pure diamond has a density of 3.52 g/cm³).

The team, led by former LLNL fellow, Peter Pauzauskie (now at the University of Washington, Department of Materials Science & Engineering), created an amorphous carbon precursor material using sol-gel processing (see pdf describing details, here) and used a diamond anvil to subject the aerogel to pressures where diamond is the stable phase of carbon. Laser heating was used to overcome the kinetic barriers of the phase transformation to nanocrystalline diamond.

A key goal of the experiment was to maintain the porous structure of the sample. The precursor aerogel is self-supporting, but the researchers note that it is still delicate - finger pressure is enough to crush it. Supercritical neon was used to apply hydrostatic pressures of 21.0 GPa, 22.5 GPa and 25.5 GPa (that’s about 3,000-3,700 ksi), and the samples were laser heated to approximately 1850 ^oC. The study made no attempt to optimize the pressure and temperature parameters.

Using Raman spectroscopy, the researchers concluded that there was not a superhard graphite phase helping to prevent pore collapse, which had been suggested as a possible mechanism for mesoporous carbon. TEM showed that diamond aerogel is a network of nanocrystals (2.5-100 nm) that appear to be connected by thin surface coatings of graphitic carbon and that the porous morphology seems to have been preserved.

It’s likely a long road from diamond anvil synthesis to a bulk processing method, but the study shows that the phase transformation from amorphous carbon to diamond can be achieved nondestructively while maintaining the porous morphology. Materials of this type are expected to have applications as tunable and optically effficient antireflective coatings, optical quantum bits, and cellular biomarkers. The unique optical, thermal, and chemical properties of a nanocrystalline diamond, porous material will lead quickly to other applications, some novel and some fairly pedestrian (but important), such as  water desalination.

As a proof-of-concept, the study showed that nondestructive phase transformation from amorphous to nanocrystalline morphologies is possible from sol-gel precursor materials, which, the authors note, opens the possibility of producing other highly porous, nanocrystalline materials such as SiO₂.

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