Monthly Archives: August 2012

Watch out Roomba! Camouflaging soft robots are on the move

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Roomba, one of the better known consumer-class robots, is a hard-bodied robot used for vacuum-cleaning (or, hoovering as the Brits say). These days scientists are working on soft-bodied robots modeled on an octopus or a starfish or a squid. A team at Harvard University has added a camouflaging feature to its soft robot.

The Aug. 16, 2012 news release on EurekAlert provides some detail about the inspiration (in a field generally known as biomimicry or biomimetics),

A team of researchers led by George Whitesides, the Woodford L. and Ann A. Flowers University Professor [and well known within the field of nanotechnology], has already broken new engineering ground with the development of soft, silicone-based robots inspired by creatures like starfish and squid.

Now, they’re working to give those robots the ability to disguise themselves.

…

“When we began working on soft robots, we were inspired by soft organisms, including octopi and squid,” Morin said [Stephen Morin, a Post-Doctoral Fellow and first author for the paper]. “One of the fascinating characteristics of these animals is their ability to control their appearance, and that inspired us to take this idea further and explore dynamic coloration. I think the important thing we’ve shown in this paper is that even when using simple systems – in this case we have simple, open-ended micro-channels – you can achieve a great deal in terms of your ability to camouflage an object, or to display where an object is.”

“One of the most interesting questions in science is ‘Why do animals have the shape, and color, and capabilities that they do?'” said Whitesides. “Evolution might lead to a particular form, but why? One function of our work on robotics is to give us, and others interested in this kind of question, systems that we can use to test ideas. Here the question might be: ‘How does a small crawling organism most efficiently disguise (or advertise) itself in leaves?’ These robots are test-beds for ideas about form and color and movement.”

Peter Reuell’s Aug. 16, 2012 article for Harvard Science, which originated the news release, describes some of the technology and capabilities,

Just as with the soft robots, the “color layers” used in the camouflage start as molds created using 3-D printers. Silicone is then poured into the molds to create micro-channels, which are topped with another layer of silicone. The layers can be created as a separate sheet that sits atop the soft robots, or incorporated directly into their structure. Once created, researchers can pump colored liquids into the channels, causing the robot to mimic the colors and patterns of its environment.

The system’s camouflage capabilities aren’t limited to visible colors though.

By pumping heated or cooled liquids into the channels, researchers can camouflage the robots thermally (infrared color). Other tests described in the Science [journal]  paper used fluorescent liquids that allowed the color layers to literally glow in the dark.

“There is an enormous amount of spectral control we can exert with this system,” Morin said. “We can design color layers with multiple channels, which can be activated independently. We’ve only begun to scratch the surface, I think, of what’s possible.”

The uses for the color-layer technology, however, don’t end at camouflage.

Just as animals use color change to communicate, Morin envisions robots using the system as a way to signal their position, both to other robots, and to the public. As an example, he cited the possible use of the soft machines during search and rescue operations following a disaster. In dimly lit conditions, he said, a robot that stands out from its surroundings (or even glows in the dark) could be useful in leading rescue crews trying to locate survivors.

So,  if the scientists are pumping the colour into the soft robot, it’s still a long way from nature’s design where the creature produces its own colourants and controls its own camouflage in response to environmental factors.

Interestingly, there’s no mention of military applications for this camouflaging robot.

Water, water, everywhere in cages, prisms, and books according to new study

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Researchers at the University of California at San Diego (UCSD) and at Emory University (Georgia, US) have a better understanding of hexamers found in the smallest of water droplets. From the Aug.16, 2012 news item on Nanowerk,

A new study by researchers at the University of California, San Diego, and Emory University has uncovered fundamental details about the hexamer structures that make up the tiniest droplets of water, the key component of life – and one that scientists still don’t fully understand.

The Aug. 15, 2012 news release by Jan Zverina for UCSD offers an explanation for why scientists would put effort into understanding the structure of tiny water droplets,

“About 60% of our bodies are made of water that effectively mediates all biological processes,” said Francesco Paesani, one of the paper’s corresponding authors who is an assistant professor in the Department of Chemistry and Biochemistry at UC San Diego and a computational researcher with the university’s San Diego Supercomputer Center (SDSC). “Without water, proteins don’t work and life as we know it wouldn’t exist. Understanding the molecular properties of the hydrogen bond network of water is the key to understanding everything else that happens in water. And we still don’t have a precise picture of the molecular structure of liquid water in different environments.”

Researchers know that the unique properties of water are due to its capability of forming a highly flexible but still dense hydrogen bond network which adapts according to the surrounding environment. As described in the JACS [Journal of the American Chemical Society] paper, researchers have determined the relative populations of the different isomers of the water hexamer as they assemble into various configurations called ‘cage’, ‘prism’, and ‘book’.

Here in more technical terms is a discussion about the importance of water hexamers,

The water hexamer is considered the smallest drop of water because it is the smallest water cluster that is three dimensional, i.e., a cluster where the oxygen atoms of the molecules do not lie on the same plane. As such, it is the prototypical system for understanding the properties of the hydrogen bond dynamics in the condensed phases because of its direct connection with ice, as well as with the structural arrangements that occur in liquid water.

This system also allows scientists to better understand the structure and dynamics of water in its liquid state, which plays a central role in many phenomena of relevance to different areas of science, including physics, chemistry, biology, geology, and climate research. For example, the hydration structure around proteins affects their stability and function, water in the active sites of enzymes affects their catalytic power, and the behavior of water adsorbed on atmospheric particles drives the formation of clouds.

The scientists have provided an illustration of two water hexamer structures,

Three-dimensional representations of the prism (left) and cage (right) structures of the water hexamer, the smallest drop of water. The mesh contours represent the actual quantum-mechanical densities of the oxygen (red) and hydrogen (white) atoms. The small yellow spheres represent the hydrogen bonds between the six water molecules. Characterizing the hydrogen-bond topology of the water hexamer at the molecular level is key to understanding the unique and often surprising properties of liquid water, our life matrix. Images courtesy of Volodymyr Babin and Francesco Paesani, UC San Diego.

Here’s the full citation for the research paper if you want to follow up on it or you can read more in either the news item or news release,

The Water Hexamer: Cage, Prism, or Both. Full Dimensional Quantum Simulations Say Both; Yimin Wang, Volodymyr Babin, Joel M. Bowman, and Francesco Paesani; J. Am. Chem. Soc., 2012, 134 (27), pp 11116–11119 DOI: 10.1021/ja304528m

The article is behind a paywall.

Commercial launch of mulitlayer nanotechnology-enabled coating from Mississauga-based (Ontario, Canada) Integran

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The Aug. 16, 2012 news item by Will Soutter for Aznonano is one of the more enigmatic pieces I’ve read,

Integran Technologies, based in Toronto [Mississauga is close to Toronto and, for familiarity’s sake, is sometimes referred to as Toronto in news releases]], has reported the commercial availability of its innovative nanostructured multilayer coating technology.

Integran Technologies’ proprietary graded, multi-layer and nanolaminate technology delivers unprecedented design options in applying novel structural and functional improvements to a broad range of semi-finished and finished components, which include polymer composites, polymers and metals.

For the life of me, I can’t find a name for or more detail about this ‘new’ technology. I checked the Aug. 14, 2012 company news release and can’t find a name. This announcement seems more focused on the patents than the technology,

Under development for several years with the support of the Canadian Government and the US Department of Defense, Integran’s proprietary graded, multi-layer and nanolaminate technology is covered by a number of specific US and foreign patent filings including the recently issued US 8,129,034 which applies to lightweight articles, precision molds, sporting goods and automotive parts, and covers specific fine-grained metallic coatings and nanolaminates containing Ni, Cu, Co, Fe, Mo, W, Zn, P, B and C.

Klaus Tomantschger, Integran’s Vice President, Intellectual Property and Licensing stated ”Integran is pleased by the US Patent Office’s determination that Integran’s unique grain-refinement technology also extends to its proprietary multi-layer laminate coating technology”. [sic]

You can find out more about Integran here and in my Sept. 4, 2008 posting, my March 26, 2012 posting, my April 16, 2012 posting, and my  May 10, 2012 posting.

Sunflower season when thoughts turn to solar power systems

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Sunflowers in Fargo, North Dakota, USA.. This image was released by the Agricultural Research Service, the research agency of the United States Department of Agriculture, with the ID K5751-1 (Downloaded from Wikipedia; http://en.wikipedia.org/wiki/Sunflower)

I love the big sunflowers, the ones where the stalks extend many feet past my 5’4″ and which are topped with those improbable, lush, huge flowers. The flowers’ height always puts me in mind of trees.  While scientists may appreciate the aesthetics and poetry as much as I do, their thoughts tend to turn to less fanciful matters. From the Aug. 16, 2012 news item on ScienceDaily,

A field of young sunflowers will slowly rotate from east to west during the course of a sunny day, each leaf seeking out as much sunlight as possible as the sun moves across the sky through an adaptation called heliotropism.

It’s a clever bit of natural engineering that inspired imitation from a UW-Madison electrical and computer engineer, who has found a way to mimic the passive heliotropism seen in sunflowers for use in the next crop of solar power systems.

Unlike other “active” solar systems that track the sun’s position with GPS and reposition panels with motors, electrical and computer engineering professor Hongrui Jiang’s concept leverages the properties of unique materials in concert to create a passive method of re-orienting solar panels in the direction of the most direct sunlight.

Here’s a demonstration of Jiang’s concept, not as a pretty as a sunflower, in a very bare bones video where you have to watch closely or you might miss the action,

Here’s a description of what you’re witnessing from Mark Reichers’ Aug. 15, 2012 news release for the University of Wisconsin-Madison,

His design, published Aug. 1 in Advanced Functional Materials and recently highlighted in Nature, employs a combination of liquid crystalline elastomer (LCE), which goes through a phase change and contracts in the presence of heat, with carbon nanotubes, which can absorb a wide range of light wavelengths.

“Carbon nanotubes have a very wide range of absorption, visible light all the way to infrared,” says Jiang. “That is something we can take advantage of, since it is possible to use sunlight to drive it directly.”

Direct sunlight hits a mirror beneath the solar panel, focused onto one of multiple actuators composed of LCE laced with carbon nanotubes. The carbon nanotubes heat up as they absorb light, and the heat differential between the environment and inside the actuator causes the LCE to shrink.

This causes the entire assembly to bow in the direction of the strongest sunlight. As the sun moves across the sky, the actuators will cool and re-expand, and new ones will shrink, re-positioning the panel over the 180 degrees of sky that the sun covers in the course of the day.

This new approach improves solar panel efficiency by 10%. This is significant in a field where an increase of even a few percentage points is cause for celebration (my July 30, 2012 posting makes reference to this phenomenon of celebrating relatively small increases in solar power systems efficiencies).

Meat fresh off the printer

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Modern Meadow Inc. promises to print meat on a 3-D printer at some time in the future but first expects to be printing leather (calfskin) by the end of this year (2012). Anna Kamenetz  in her Aug. 15, 2012 (?) article for Fast Company’s Co.Exist website notes,

… Modern Meadow [MM] co-founder and CEO Andras Forgacs, explains, this new venture is, ahem, a natural outgrowth of that one [a company called Organovo, a startup specializing in 3-D printed, bioengineered organs founded by Andras’ father, Gabor Forgacs who’s co-founded MM with Andras]. “The idea struck us that if we can make medical-grade tissues that are good enough for drug companies, good enough for patients, then certainly we can find other applications for tissue engineering.” Forgacs does seem to understand how terrifying that sounds, which is why his startup has been relatively press-shy until the announcement this morning, and also why they’re starting with wearable, not edible, products. Still, he argues that cell culturing for food is as old as, well, culture itself:

…

“Whether you’re brewing beer or making yogurt, you’re really doing cell culture,” he [Andras Forgacs] says. In this case, though, the process involves biopsying a living animal (a relatively harmless procedure), isolating the desired cells, growing large numbers of them, and preparing them into cell aggregates–spheres of tens of thousands of cells. These aggregates can then become the raw material for more industrial processes. In the case of complete organs, that process is something like 3-D printing. For calfskin–the product that Modern Meadow intends to turn out by the end of the year–it would resemble something more like regular printing or weaving. The end result will be a hairless, pre-tanned, soft, smooth, chemical- and waste-free material in any color or pattern imaginable …

It’s not easy to find information about this company (they don’t seem to have a website) and, I gather from elsewhere in Kamenetz’s article, they’ve been media shy until now.

The US Dept. of Agriculture (USDA)  provides some information about a small business grant they gave to Modern Meadow for the 2012 fiscal year. From the Modern Meadow page on the USDA Research, Education & Economics Information System website, here are the project goals,

The objective of this proposal is to construct muscle tissues by a novel and versatile tissue engineering technology and to assess their texture and composition for use as minced meat. The patented “print-based” technology has several distinguishing features. It is scaffold-free – it does not rely on any artificial material to form the desired structure. The process to build a tissue construct utilizes the automated deposition of convenient multicellular units, suitable for rapid prototyping and high-throughput production. The method has solid scientific underpinning based on tissue self-assembly processes akin to those evident in early morphogenesis (i.e. tissue fusion, engulfment and cell sorting). The ultimate product that will be developed based on the proposed studies is an animal muscle strip that can be used as minced meat for the preparation of sausages, patties and nuggets. The two aims that will be pursued in this Phase I application are 1) to fabricate 3D cellular sheets composed of porcine cells and 2) to mature the cellular sheets into muscle tissue and measure its meat characteristics. The related technical objectives are 1) to determine the optimal cellular composition (type and ratio of muscle cells, fibroblasts and adipocytes) to produce “easy-to-handle” cellular sheets and 2) to find the most efficient stimulation method (mechanical, electrical or a combination of both) to achieve muscle formation with similar mechanical and biochemical properties to meat. The successful completion of the proposed project will provide the optimal parameters and conditions for engineering strips of mammalian muscle tissue ((2 x 1 x 0.5) cm3) with appropriate mechanical and biochemical properties to be used as minced lean meat. The building of larger pieces, that may need to be perfused and engineered around bio-printed blood vessels, would be carried out in Phase II.

If you’d told me about ‘vat’ or ‘printed’ meat five years ago I would have been horrified and suspicious. I’m somewhat less horrified today but still suspicious or perhaps I should call it, cautious.

Calling all scientists with a good command of English and expertise on medical devices containing nanomaterials

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The Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) needs experts because it has been asked by the European Commission to asses the use of nanomaterials in medical devices. From the Aug. 15, 2012 news item on Nanowerk,

The relevant SCENIHR working group has identified a need in the field of medical devices containing nanomaterials. In line with the Rules of procedure (pdf) of the Scientific Committees, a call for expression of interest for experts in this topic is launched.

To allow for a comprehensive assessment, experts in various scientific fields related to the safety of medical devices containing nanomaterials are encouraged to apply. Experience in risk assessment would be an advantage.

The deadline for submission for this call for experts is 1 October 2012 (kindly note that the registration to the database of experts with regard to the general work of the Scientific Committees is permanently open). Applicants are requested to indicate “SCENIHR: Medical devices Nano – call for experts” in the subject title of the message sent with their application.

The detailed description of the mandate for this request can be found here. It includes details such as this from the  introduction,

Today, a more widespread application of nanotechnologies and nanomaterials is imminent or already occurring in many areas, including health care. For nanomedicine, the three largest areas of application are diagnostics, drug delivery and regenerative medicine (ETP Nanomedicine 2009). In addition there are applications in surgery and thermotherapy (Vauthier et al. 2011). In the field of medical devices, the following cases of alleged use of nanomaterials have been identified by Notified Bodies:

– Carbon nanotubes in bone cements;

– Nanopaste hydroyapatite powder for bone void filling;

– Polymer setting material with nanoparticles in dental cements;

– Polycrystalline nanoceramics in dental restorative materials;

– Nanosilver or other nanomaterials used as coatings on implants and catheters;

– Nanosilver used as an antibacterial agent, for example in wound dressings (see also Wijnhoven et al. 2009).

Furthermore, there are reports on iron-oxide nanoparticles injected into tumour cells to be heated-up by radiation or an external magnetic field1. This type of use has not yet been clearly attributed to the legislation on medicines or to the legislation on medical devices. On one hand, the immediate effect is mechanical as the tumour cells burst. On the other hand, one might regard the legislation on medicines applicable as the burst cells are metabolised at a later point in time.

Although the general risk assessment requirements applicable for materials used in medical devices and previous scientific opinions on risk assessment of nanomaterials (see e.g. SCENIHR 2006, 2007 and 2009) are useful when assessing nanomaterials for medical applications, there is a need for further clarification in the risk assessment of such products. (p. 1)

The Terms of Reference include,

This evaluation shall take into account different categories of medical devices such as:

a.. Non-invasive medical devices, e.g. devices coming into contact with the

intact skin,

b. Invasive devices (surgical or not), e.g.:

o woundcare materials,

o implantable medical devices,

o dental and bone fillings and cements,

o injectable nanomaterials.

In this assessment, where relevant, the SCENIHR is invited to differentiate between free, fixed, and encapsulated nanomaterials. (p. 2)

The deadline listed in the mandate is March 2013. Presumably this is the deadline for the assessment itself while the deadline to apply as an expert is Oct. 10, 2012 according to the SCENIHR webpage for the August 2012 Call for Information on the Safety of Devices Containing Nanomaterials.

ETA Aug.15, 2012 11:20 am PDT: Given that I originally misspelled the word expertise in my headline for this post, maybe I need to check my own expertise … with English.

The Avro Arrow, Hy-Power Nano, and Dr. Hadi Mahabadi

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Before launching into the nano part of this story, here’s a brief description  for anyone who’s not familiar with the legendary Canadian Avro Arrow airplane, from the Wikipedia essay,

The Avro Canada CF-105 Arrow was a delta-winged interceptor aircraft, designed and built by Avro Aircraft Limited (Canada) in Malton, Ontario, as the culmination of a design study that began in 1953. Considered to be both an advanced technical and aerodynamic achievement for the Canadian aviation industry, the CF-105 held the promise of Mach 2 speeds at altitudes exceeding 50,000 ft (15,000 m), and was intended to serve as the Royal Canadian Air Force’s (RCAF) primary interceptor in the 1960s and beyond.

Not long after the 1958 start of its flight test program, the development of the Arrow (including its Orenda Iroquois jet engines) was abruptly and controversially halted before the project review had taken place, sparking a long and bitter political debate.

The controversy engendered by the cancellation and subsequent destruction of the aircraft in production, remains a topic for debate among historians, political observers and industry pundits. “This action effectively put Avro out of business and its highly skilled engineering and production personnel scattered… The incident was a traumatic one… and to this day, many mourn the loss of the Arrow.”

Apparently, one young engineer moved on from the Avro experience to found his own company, Hy-Power Coatings Ltd.  which recently begat Hy-Power Nano. From the Hy-Power Nano History page,

In 1966, an engineer from Canada’s famed Avro Arrow Project took his unique knowledge of coatings and incorporated Hy-Power Coatings Limited in Brampton, Ontario. In 1975, Joseph G. Grzyb became President and principal owner of this privately held company. Mr. Grzyb was able to harness coatings expertise to evolve the electrostatic paint process and dozens of other coating innovations. A commitment to coating service excellence through innovation and customer service have made Hy-Power a premier coatings service provider.

Today, Hy-Power CEO Joseph Grzyb leads a strong, tenured team of coating professionals that service a loyal blue chip customer base.

Hy-Power Coatings’ experience resides in the finishing and refinishing of common substrates (metal, masonry, plastic, etc.). The company has strong core competencies in paint and coating application, as well as innovating coating products and application techniques.

Hy-Power has successfully improved many coating products to more environmentally friendly water-based compositions without sacrificing finish quality or durability.

There’s no mention in the company history of when they included a nano subsidiary with the main business but it’s somewhat recent (as per the news article by Peter Criscione which is excerpted further in this posting)  as they appear to be in the early stages of product development with something called, Thermal Liquid Glass listed on the home page,

 … a clear nano-enhanced coating for glass that maintains light clarity and blocks UV and R rays.

The company (Hy-Power Nano) has just announced the appointment of a new Chief Operating Officer, Dr. Hadi Mahabadi. From the Aug. 14, 2012 article by Peter Criscione for the Brampton Guardian (Ontario, Canada),

In 2010, Hy-Power Nano Inc. was established as Hy-Power Coatings’ “scientific branch” to further research and development of proprietary nano-based insulating coatings.
Although just getting started, Hy-Power Nano, which employs about 50 people, has taken major steps to boost its brand including bringing Mahabadi on to help “bring exceptional products to market.”
Previously, Dr. Mahabadi was vice president and director of the Xerox Research Centre of Canada, where he spearheaded many innovations and commercialized technologies.
Mahabadi, 66, spent 30 years with Xerox, rising to the company’s top Canadian research position.
He retired from Xerox in September 2011 with more than 100 published scientific papers and 70 U.S. patents to his name, as well as receiving numerous honours.
In June, he received an Order of Canada for his internationally recognized innovations in the field of polymer science and “his commitment to promoting scientific development in Canada.”
Mahabadi is also a recipient of the Robert F. Reed Technology Medal (the Printing Industries of America’s highest honour), two Xerox President Awards (the corporation’s highest honour for individual achievement) and the University of Waterloo’s Engineering Alumni’s Achievement Medal.
He is also a Fellow of the Chemical Institute of Canada, a Fellow of the International Union of Pure and Applied Chemistry, and a Fellow of the Canadian Academy of Engineering.
Mahabadi is currently president of CanWin Consulting Inc, which provides a range of services for innovation to start-up and other small and medium enterprises in Canada.
His credentials are impeccable, said Joseph Grzyb, Hy-Power Nano CEO.
“Dr. Hadi Mahabadi offered tremendous insights when he joined our board in February 2012 and also served as a consultant,” Grzyb said.
“We quickly realized he could play a more active role in the company by becoming COO. He’s a great addition to the Hy-Power Nano team.”
Mahabadi said he was attracted to the job because he’s intrigued with the nanotechnology commercialization work the company is doing.

Congratulations  to Dr. Mahabadi!

For anyone interested in more information about thermochromic windows, there’s my July 11, 2012 posting where I featured RavenBrick and its thermochromic windows.

Photo-acoustic alarms for poison gas

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Alexander Graham Bell discovered the photoacoustic effect which researchers at the US Army Research Laboratory are attempting to exploit for the purpose of sensing poison gases. From the Aug. 14, 2012 news item on ScienceDaily,

To warn of chemical attacks and help save lives, it’s vital to quickly determine if even trace levels of potentially deadly chemicals — such as the nerve gas sarin and other odorless, colorless agents — are present. U.S. Army researchers have developed a new chemical sensor that can simultaneously identify a potentially limitless numbers of agents, in real time.

…

The new system is based on a phenomenon known as the photoacoustic effect, which was discovered by Alexander Graham Bell, in which the absorption of light by materials generates characteristic acoustic waves. By using a laser and very sensitive microphones — in a technique called laser photoacoustic spectroscopy (LPAS) — vanishingly low concentrations of gases, at parts per billion or even parts per trillion levels, can be detected. The drawback of traditional LPAS systems, however, is that they can identify only one chemical at a time.

Here’s how the researchers dealt with the limitation of being able to identify only one chemical at a time (from the news item),

[Kristan Gurton, an experimental physicist at the U.S. Army Research Laboratory (ARL) in Adelphi, Md] “As I started looking into the chemical/biological detection problem, it became apparent that multiple LPAS absorption measurements — representing an ‘absorption spectrum’ — might provide the added information required in any detection and identification scheme.”

To create such a multi-wavelength LPAS system, Gurton, along with co-authors Melvin Felton and Richard Tober of the ARL, designed a sensor known as a photoacoustic cell. This hollow, cylindrical device holds the gas being sampled and contains microphones that can listen for the characteristic signal when light is applied to the sample.

In this experiment, the researchers used a specialized cell that allows different gases to flow through the device for testing. As the vapor of five nerve agent mimics was flowed in, three laser beams, each modulated at a different frequency in the acoustic range, were propagated through the cell.

“A portion of the laser power is absorbed, usually via molecular transitions, and this absorption results in localized heating of the gas,” Gurton explains. Molecular transitions occur when the electrons in a molecule are excited from one energy level to a higher energy level. “Since gas dissipates thermal energy fairly quickly, the modulated laser results in a rapid heat/cooling cycle that produces a faint acoustic wave,” which is picked up by the microphone. Each laser in the system will produce a single tone, so, for example, six laser sources have six possible tones. “Different agents will affect the relative ‘loudness’ of each tone,” he says, “so for one gas, some tones will be louder than others, and it is these differences that allow for species identification.”

The signals produced by each laser were separated using multiple “lock-in” amplifiers — which can extract signals from noisy environments — each tuned for a specific laser frequency. Then, by comparing the results to a database of absorption information for a range of chemical species, the system identified each of the five gases.

Because it is optically based, the method allows for instant identification of agents, as long as the signal-to-noise ratio, which depends on both laser power and the concentration of the compound being measured, is sufficiently high, and the material in question is in the database.

But they still need to invent a device before they can take this process out of the laboratory,

Before a device based on the technique could be used in the field, Gurton says, a quantum cascade (QC) laser array with at least six “well-chosen” mid-infrared (MidIR) laser wavelengths would need to be available.

Here’s the citation for the article, which is behind a paywall,

Kristan P. Gurton, Melvin Felton, and Richard Tober. Selective real-time detection of gaseous nerve agent simulants using multiwavelength photoacoustics. Opt. Lett., 37, 3474-3476 (2012) [link]

There are more details in the ScienceDaily news item or you can check out the Aug. 14, 2012 (?) news release from the Optical Society of America.

I wonder what this research sounds like, unfortunately they didn’t include any audio files with the news release from the Optics Society of America or the news item on ScienceDaily.

Batteries made of wood and the mechanical properties of plants

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According to Ariel Schwartz in an Aug. 14, 2012 (?) article for Fast Company’s Co.Exist website, batteries made from wood waste may be in our future (Note: I have removed a link),

Researchers from Poznan University of Technology in Poland and Linköping University in Sweden have figured out how to combine lignin with polypyrrole (a conductive polymer) to create a battery cathode that could one day be used in energy storage. The lignin acts as an insulator, while the polypyrrole holds an electric charge.

The discovery is a potential boon for the renewable energy world. As the researchers explain in the journal Science, “Widespread application of electrical power storage may require more abundant materials than those available in inorganics (which often require rare metals), and at a lower cost. Materials for charge storage are desired from easily accessible and renewable sources. Combining cellulose materials and conjugated polymers for charge storage has … attracted attention.”

For anyone (like me) who’s heard the word lignin but doesn’t know the precise meaning, here’s a definition from a Wikipedia essay (Note: I have removed links and footnotes),

Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood. It is one of the most abundant organic polymers on Earth, exceeded only by cellulose, employing 30% of non-fossil organic carbon, and constituting from a quarter to a third of the dry mass of wood.

This next item also mentions lignin but in reference to mechanical properties that engineers are observing in plant cells.  From the Aug. 14, 2012 news item on Nanowerk,

From an engineer’s perspective, plants such as palm trees, bamboo, maples and even potatoes are examples of precise engineering on a microscopic scale. Like wooden beams reinforcing a house, cell walls make up the structural supports of all plants. Depending on how the cell walls are arranged, and what they are made of, a plant can be as flimsy as a reed, or as sturdy as an oak.

An MIT researcher has compiled data on the microstructures of a number of different plants, from apples and potatoes to willow and spruce trees, and has found that plants exhibit an enormous range of mechanical properties, depending on the arrangement of a cell wall’s four main building blocks: cellulose, hemicellulose, lignin and pectin.

The news item was originated at the Massachusetts Institute of Technology (MIT) by Jennifer Chu’s Aug. 14, 2012 news release,

Lorna Gibson, the [researcher] at MIT, says understanding plants’ microscopic organization may help engineers design new, bio-inspired materials.

“If you look at engineering materials, we have lots of different types, thousands of materials that have more or less the same range of properties as plants,” Gibson says. “But here the plants are, doing it arranging just four basic constituents. So maybe there’s something you can learn about the design of engineered materials.”

A paper detailing Gibson’s findings has been published this month [freely accessible] in the Journal of the Royal Society Interface.

To Gibson, a cell wall’s components bear a close resemblance to certain manmade materials. For example, cellulose, hemicellulose and lignin can be as stiff and strong as manufactured polymers. A plant’s cellular arrangement can also have engineering parallels: cells in woods, for instance, are aligned, similar to engineering honeycombs, while polyhedral cell configurations, such as those found in apples, resemble some industrial foams.

To explore plants’ natural mechanics, Gibson focused on three main plant materials: woods, such as cedar and oak; parenchyma cells, which are found in fruits and root vegetables; and arborescent palm stems, such as coconut trees. She compiled data from her own and other groups’ experiments and analyzed two main mechanical properties in each plant: stiffness and strength.

Among all plants, Gibson observed wide variety in both properties. Fruits and vegetables such as apples and potatoes were the least stiff, while the densest palms were 100,000 times stiffer. Likewise, apples and potatoes fell on the lower end of the strength scale, while palms were 1,000 times stronger.

“There are plants with properties over that whole range,” Gibson says. “So it’s not like potatoes are down here, and wood is over there, and there’s nothing in between. There are plants with properties spanning that whole huge range. And it’s interesting how the plants do that.”

Since I’m always interested in trees, from Chu’s news release,

In trees such as maples and oaks, cells grow and multiply in the cambium layer, just below the bark, increasing the diameter of the trees. The cell walls in wood are composed of a primary layer with cellulose fibers randomly spread throughout it. Three secondary layers lie underneath, each with varying compositions of lignin and cellulose that wind helically through each layer.

Taken together, the cell walls occupy a large portion of a cell, providing structural support. The cells in woods are organized in a honeycomb pattern — a geometric arrangement that gives wood its stiffness and strength.

Parenchyma cells, found in fruits and root vegetables, are much less stiff and strong than wood. The cell walls of apples, potatoes and carrots are much thinner than in wood cells, and made up of only one layer. Cellulose fibers run randomly throughout this layer, reinforcing a matrix of hemicellulose and pectin. Parenchyma cells have no lignin; combined with their thin walls and the random arrangement of their cellulose fibers, Gibson says, this may explain their cell walls’ low stiffness. The cells in each plant are densely packed together, similar to industrial foams used in mattresses and packaging.

Unlike woody trees that grow in diameter over time, the stems of arborescent palms such as coconut trees maintain similar diameters throughout their lifetimes. Instead, as the stem grows taller, palms support this extra weight by increasing the thickness of their cell walls. A cell wall’s thickness depends on where it is along a given palm stem: Cell walls are thicker at the base and periphery of stems, where bending stresses are greatest.

There’s even a nanotechnology slant to this story, from Chu’s news release,

Gibson sees plant mechanics as a valuable resource for engineers designing new materials. For instance, she says, researchers have developed a wide array of materials, from soft elastomers to stiff, strong alloys. Carbon nanotubes have been used to reinforce composite materials, and engineers have made honeycomb-patterned materials with cells as small as a few millimeters wide. But researchers have been unable to fabricate cellular composite materials with the level of control that plants have perfected.

“Plants are multifunctional,” Gibson says. “They have to satisfy a number of requirements: mechanical ones, but also growth, surface area for sunlight and transport of fluids. The microstructures plants have developed satisfy all these requirements. With the development of nanotechnology, I think there is potential to develop multifunctional engineering materials inspired by plant microstructures.”

Given the problems with the forestry sector, these developments (wooden batteries and engineering materials inspired by plant cell walls) should excite some interest.