Tag Archives: Saudi Arabia

Nano-alchemy: silver nanoparticles that look like and act like gold

This work on ‘nano-alchemy’ comes out of the King Abduhllah University of Science and Technology (KAUST) according to a Sept. 22, 2015 article by Lisa Zynga for phys.org (Note: A link has been removed),

In an act of “nano-alchemy,” scientists have synthesized a silver (Ag) nanocluster that is virtually identical to a gold (Au) nanocluster. On the outside, the silver nanocluster has a golden yellow color, and on the inside, its chemical structure and properties also closely mimic those of its gold counterpart. The work shows that it may be possible to create silver nanoparticles that look and behave like gold despite underlying differences between the two elements, and could lead to creating similar analogues between other pairs of elements.

“In some aspects, this is very similar to alchemy, but we call it ‘nano-alchemy,'” Bakr [Osman Bakr, Associate Professor of Materials Science and Engineering at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia] told Phys.org. “When we first encountered the optical spectrum of the silver nanocluster, we thought that we may have inadvertently switched the chemical reagents for silver with gold, and ended up with gold nanoparticles instead. But repeated synthesis and measurements proved that the clusters were indeed silver and yet show properties akin to gold. It was really surprising to us as scientists to find not only similarities in the color and optical properties, but also the X-ray structure.”

In their study, the researchers performed tests demonstrating that the silver and gold nanoclusters have very similar optical properties. Typically, silver nanoclusters are brown or red in color, but this one looks just like gold because it emits light at almost the same wavelength (around 675 nm) as gold. The golden color can be explained by the fact that both nanoclusters have virtually identical crystal structures.

The question naturally arises: why are these silver and gold nanoclusters so similar, when individual atoms of silver and gold are very different, in terms of their optical and structural properties? As Bakr explained, the answer may have to do with the fact that, although larger in size, the nanoclusters behave like “superatoms” in the sense that their electrons orbit the entire nanocluster as if it were a single giant atom. These superatomic orbitals in the silver and gold nanoclusters are very similar, and, in general, an atom’s electron configuration contributes significantly to its properties.

Here’s one of the images used to illustrate Zynga’s article and the paper published by the American Chemical Society,

(Left) Optical properties of the silver and gold nanoclusters, with the inset showing photographs of the actual color of the synthesized nanoclusters. The graph shows the absorption (solid lines) and normalized emission (dotted lines) spectra. (Right) Various representations of the X-ray structure of the silver nanocluster. Credit: Joshi, et al. ©2015 American Chemical Society

(Left) Optical properties of the silver and gold nanoclusters, with the inset showing photographs of the actual color of the synthesized nanoclusters. The graph shows the absorption (solid lines) and normalized emission (dotted lines) spectra. (Right) Various representations of the X-ray structure of the silver nanocluster. Credit: Joshi, et al. ©2015 American Chemical Society

I encourage you to read Zynga’s article in its entirety. For the more technically inclined, here’s a link to and a citation for the researchers’ paper,

[Ag25(SR)18]: The “Golden” Silver Nanoparticle by Chakra P. Joshi, Megalamane S. Bootharaju, Mohammad J. Alhilaly, and Osman M. Bakr.J. Am. Chem. Soc., 2015, 137 (36), pp 11578–11581 DOI: 10.1021/jacs.5b07088 Publication Date (Web): August 31, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Tobacco Indemnification and Community Revitalization Commission supports nanomaterial development with a $2M grant

Tobacco growing is not as lucrative as it once was. Worldwide anti-smoking legislation and health campaigns against smoking have had an effect on the industry and the farmers who grow tobacco. With that in mind, the June 10, 2015 news item on Azonano suggests that the industry and the farmers might be trying to find other uses for tobacco,

The Tobacco Commission [aka Tobacco Indemnification and Community Revitalization Commission] voted unanimously to award the Center for Advanced Engineering & Research a $2 million research and development grant, 100% of which will directly support NanoTouch Materials’ continued development of their NanoSeptic surfaces. This funding will be used to research new materials and advanced manufacturing processes, and build a dedicated fabrication facility in Bedford County [state of Virginia].

A June 9, 2015 NanoTouch news release on prnewswire.com, which originated the news item, describes the deal in more detail but offers no indication as to how tobacco might factor into the research (Note: A link has been removed),

“What makes research and development of NanoSeptic products complex and expensive is the multiple areas of scientific expertise required,” says NanoTouch co-founder Mark Sisson. “This funding will allow us to continue working with some of the best scientific minds in material science, nanotechnology, polymers and biotechnology.”

The research component of this grant will be focused on the development of the 5th generation of the NanoSeptic surface. Initial lab testing on early prototypes of the technology resulted in a surface that was 1,000 times more effective than the previous generation, achieving almost a six-log reduction.

Effectiveness of the current NanoSeptic surface has been extensively studied both by an independent FDA compliant lab and university research centers worldwide, including Saudi Arabia and South Korea. These studies utilize internationally recognized standard testing protocols against a variety of pathogens including E. coli, MRSA, Staph, Norovirus and the human Coronavirus, a strain of which is causing MERS outbreaks in the Middle East and Korea.

“NanoSeptic products present a great growth opportunity for this region,” says Bob Bailey, executive director of CAER. “The Center for Advanced Engineering and Research [this appears to be a wholly NanoTouch-owned research group] is excited to be part of this project and we believe that our strong research partnerships with multiple Virginia universities will prove to be a significant asset.”

As part of this three-year initiative, NanoTouch Materials is expected to grow their workforce in Bedford County, VA to a total of 14 employees, and an estimated 37 employees in five years. NanoTouch is also expected to invest $1 million in facilities and advanced manufacturing equipment.

“Virtually every firm or project with which the Tobacco Commission partners has a common characteristic: a tremendous potential to grow.  NanoSeptic is an ideal example of this.  It’s easy to see how big the potential is in healthcare, public and commercial transportation, and the hospitality industry,” says Delegate Kathy Byron, Chair of the Research & Development Committee. “That potential is emblematic of our entire region, and the reestablishment of our manufacturing community.  Once again, companies in Central and Southside Virginia are making products that are being used worldwide.”

While an entire line of NanoSeptic products have been developed and are being distributed to 29 countries, the company also plans to spend significant funding to conduct market research in the healthcare, education, facility management, commercial janitorial and food service industries. This market research will guide future product development and uncover specific ways that self-cleaning surfaces can be used to improve healthcare outcomes, reduce employee and student absenteeism, and broadly improve community health.

“While the vetting process for the grant was exhaustive, we’re grateful for the support of the Tobacco Commission and the Economic Development Authority of Bedford County in our mission of providing cleaner, healthier places in which to live, work and play,” says NanoTouch co-founder Dennis Hackemeyer. “And our investors couldn’t be happier with the company receiving funding that will accelerate growth without diluting their investment.”

The news release goes on to describe the funding agency,

The Tobacco Indemnification and Community Revitalization Commission is a 31-member body whose mission is to promote economic growth and development in tobacco-dependent communities using proceeds of the national tobacco settlement.  The Commission has awarded 1,831 grants totaling more than $1,072,922,288 across the tobacco region of the Commonwealth. http://www.tic.virginia.gov

I have mentioned NanoTouch before in an April 24, 2013 posting where I also expressed some interest in getting more technical information about the company’s products. In 2013, the company was introducing its product, NanoSeptic, into schools in the Bellmore-Merrick School District of New York.

Sealing graphene’s defects to make a better filtration device

Making a graphene filter that allows water to pass through while screening out salt and/or noxious materials has been more challenging than one might think. According to a May 7, 2015 news item on Nanowerk, graphene filters can be ‘leaky’,

For faster, longer-lasting water filters, some scientists are looking to graphene –thin, strong sheets of carbon — to serve as ultrathin membranes, filtering out contaminants to quickly purify high volumes of water.

Graphene’s unique properties make it a potentially ideal membrane for water filtration or desalination. But there’s been one main drawback to its wider use: Making membranes in one-atom-thick layers of graphene is a meticulous process that can tear the thin material — creating defects through which contaminants can leak.

Now engineers at MIT [Massachusetts Institute of Technology], Oak Ridge National Laboratory, and King Fahd University of Petroleum and Minerals (KFUPM) have devised a process to repair these leaks, filling cracks and plugging holes using a combination of chemical deposition and polymerization techniques. The team then used a process it developed previously to create tiny, uniform pores in the material, small enough to allow only water to pass through.

A May 8, 2015 MIT news release (also on EurkeAlert), which originated the news item, expands on the theme,

Combining these two techniques, the researchers were able to engineer a relatively large defect-free graphene membrane — about the size of a penny. The membrane’s size is significant: To be exploited as a filtration membrane, graphene would have to be manufactured at a scale of centimeters, or larger.

In experiments, the researchers pumped water through a graphene membrane treated with both defect-sealing and pore-producing processes, and found that water flowed through at rates comparable to current desalination membranes. The graphene was able to filter out most large-molecule contaminants, such as magnesium sulfate and dextran.

Rohit Karnik, an associate professor of mechanical engineering at MIT, says the group’s results, published in the journal Nano Letters, represent the first success in plugging graphene’s leaks.

“We’ve been able to seal defects, at least on the lab scale, to realize molecular filtration across a macroscopic area of graphene, which has not been possible before,” Karnik says. “If we have better process control, maybe in the future we don’t even need defect sealing. But I think it’s very unlikely that we’ll ever have perfect graphene — there will always be some need to control leakages. These two [techniques] are examples which enable filtration.”

Sean O’Hern, a former graduate research assistant at MIT, is the paper’s first author. Other contributors include MIT graduate student Doojoon Jang, former graduate student Suman Bose, and Professor Jing Kong.

A delicate transfer

“The current types of membranes that can produce freshwater from saltwater are fairly thick, on the order of 200 nanometers,” O’Hern says. “The benefit of a graphene membrane is, instead of being hundreds of nanometers thick, we’re on the order of three angstroms — 600 times thinner than existing membranes. This enables you to have a higher flow rate over the same area.”

O’Hern and Karnik have been investigating graphene’s potential as a filtration membrane for the past several years. In 2009, the group began fabricating membranes from graphene grown on copper — a metal that supports the growth of graphene across relatively large areas. However, copper is impermeable, requiring the group to transfer the graphene to a porous substrate following fabrication.

However, O’Hern noticed that this transfer process would create tears in graphene. What’s more, he observed intrinsic defects created during the growth process, resulting perhaps from impurities in the original material.

Plugging graphene’s leaks

To plug graphene’s leaks, the team came up with a technique to first tackle the smaller intrinsic defects, then the larger transfer-induced defects. For the intrinsic defects, the researchers used a process called “atomic layer deposition,” placing the graphene membrane in a vacuum chamber, then pulsing in a hafnium-containing chemical that does not normally interact with graphene. However, if the chemical comes in contact with a small opening in graphene, it will tend to stick to that opening, attracted by the area’s higher surface energy.

The team applied several rounds of atomic layer deposition, finding that the deposited hafnium oxide successfully filled in graphene’s nanometer-scale intrinsic defects. However, O’Hern realized that using the same process to fill in much larger holes and tears — on the order of hundreds of nanometers — would require too much time.

Instead, he and his colleagues came up with a second technique to fill in larger defects, using a process called “interfacial polymerization” that is often employed in membrane synthesis. After they filled in graphene’s intrinsic defects, the researchers submerged the membrane at the interface of two solutions: a water bath and an organic solvent that, like oil, does not mix with water.

In the two solutions, the researchers dissolved two different molecules that can react to form nylon. Once O’Hern placed the graphene membrane at the interface of the two solutions, he observed that nylon plugs formed only in tears and holes — regions where the two molecules could come in contact because of tears in the otherwise impermeable graphene — effectively sealing the remaining defects.

Using a technique they developed last year, the researchers then etched tiny, uniform holes in graphene — small enough to let water molecules through, but not larger contaminants. In experiments, the group tested the membrane with water containing several different molecules, including salt, and found that the membrane rejected up to 90 percent of larger molecules. However, it let salt through at a faster rate than water.

The preliminary tests suggest that graphene may be a viable alternative to existing filtration membranes, although Karnik says techniques to seal its defects and control its permeability will need further improvements.

“Water desalination and nanofiltration are big applications where, if things work out and this technology withstands the different demands of real-world tests, it would have a large impact,” Karnik says. “But one could also imagine applications for fine chemical- or biological-sample processing, where these membranes could be useful. And this is the first report of a centimeter-scale graphene membrane that does any kind of molecular filtration. That’s exciting.”

De-en Jiang, an assistant professor of chemistry at the University of California at Riverside, sees the defect-sealing technique as “a great advance toward making graphene filtration a reality.”

“The two-step technique is very smart: sealing the defects while preserving the desired pores for filtration,” says Jiang, who did not contribute to the research. “This would make the scale-up much easier. One can produce a large graphene membrane first, not worrying about the defects, which can be sealed later.”

I have featured graphene and water desalination work before  from these researchers at MIT in a Feb. 27, 2014 posting. Interestingly, there was no mention of problems with defects in the news release highlighting this previous work.

Here’s a link to and a citation for the latest paper,

Nanofiltration across Defect-Sealed Nanoporous Monolayer Graphene by Sean C. O’Hern, Doojoon Jang, Suman Bose, Juan-Carlos Idrobo, Yi Song §, Tahar Laoui, Jing Kong, and Rohit Karnik. Nano Lett., Article ASAP DOI: 10.1021/acs.nanolett.5b00456 Publication Date (Web): April 27, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Spray-on solar cells from the University of Toronto (Canada)

It’s been a while since there’s been a solar cell story from the University of Toronto (U of T) and I was starting to wonder if Ted (Edward) Sargent had moved to another educational institution. The drought has ended with the announcement of three research papers being published by researchers from Sargent’s U of T laboratory. From a Dec. 5, 2014 ScienceDaily news item,

Pretty soon, powering your tablet could be as simple as wrapping it in cling wrap.

That’s Illan Kramer’s … hope. Kramer and colleagues have just invented a new way to spray solar cells onto flexible surfaces using miniscule light-sensitive materials known as colloidal quantum dots (CQDs) — a major step toward making spray-on solar cells easy and cheap to manufacture.

A Dec. 4, 2014 University of Toronto news release (also on EurekAlert) by Marit Mitchell, which originated the news item, gives a bit more detail about the technology (Note: Links have been removed),

 Solar-sensitive CQDs printed onto a flexible film could be used to coat all kinds of weirdly-shaped surfaces, from patio furniture to an airplane’s wing. A surface the size of a car roof wrapped with CQD-coated film would produce enough energy to power three 100-watt light bulbs – or 24 compact fluorescents.

He calls his system sprayLD, a play on the manufacturing process called ALD, short for atomic layer deposition, in which materials are laid down on a surface one atom-thickness at a time.

Until now, it was only possible to incorporate light-sensitive CQDs onto surfaces through batch processing – an inefficient, slow and expensive assembly-line approach to chemical coating. SprayLD blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic, like printing a newspaper by applying ink onto a roll of paper. This roll-to-roll coating method makes incorporating solar cells into existing manufacturing processes much simpler. In two recent papers in the journals Advanced Materials and Applied Physics Letters, Kramer showed that the sprayLD method can be used on flexible materials without any major loss in solar-cell efficiency.

Kramer built his sprayLD device using parts that are readily available and rather affordable – he sourced a spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store.

“This is something you can build in a Junkyard Wars fashion, which is basically how we did it,” says Kramer. “We think of this as a no-compromise solution for shifting from batch processing to roll-to-roll.”

“As quantum dot solar technology advances rapidly in performance, it’s important to determine how to scale them and make this new class of solar technologies manufacturable,” said Professor Ted Sargent, vice-dean, research in the Faculty of Applied Science & Engineering at University of Toronto and Kramer’s supervisor. “We were thrilled when this attractively-manufacturable spray-coating process also led to superior performance devices showing improved control and purity.”

In a third paper in the journal ACS Nano, Kramer and his colleagues used IBM’s BlueGeneQ supercomputer to model how and why the sprayed CQDs perform just as well as – and in some cases better than – their batch-processed counterparts. This work was supported by the IBM Canada Research and Development Centre, and by King Abdullah University of Science and Technology.

For those who would like to see the sprayLD device,

Here are links and citation for all three papers,

Efficient Spray-Coated Colloidal Quantum Dot Solar Cells by Illan J. Kramer, James C. Minor, Gabriel Moreno-Bautista, Lisa Rollny, Pongsakorn Kanjanaboos, Damir Kopilovic, Susanna M. Thon, Graham H. Carey, Kang Wei Chou, David Zhitomirsky, Aram Amassian, and Edward H. Sargent. Advanced Materials DOI: 10.1002/adma.201403281 Article first published online: 10 NOV 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Colloidal quantum dot solar cells on curved and flexible substrates by Illan J. Kramer, Gabriel Moreno-Bautista, James C. Minor, Damir Kopilovic, and Edward H. Sargent. Appl. Phys. Lett. 105, 163902 (2014); http://dx.doi.org/10.1063/1.4898635 Published online 21 October 2014

© 2014 AIP Publishing LLC

Electronically Active Impurities in Colloidal Quantum Dot Solids by Graham H. Carey, Illan J. Kramer, Pongsakorn Kanjanaboos, Gabriel Moreno-Bautista, Oleksandr Voznyy, Lisa Rollny, Joel A. Tang, Sjoerd Hoogland, and Edward H. Sargent. ACS Nano, 2014, 8 (11), pp 11763–11769 DOI: 10.1021/nn505343e Publication Date (Web): November 6, 2014

Copyright © 2014 American Chemical Society

All three papers are behind paywalls.

Given the publication dates for the papers, this looks like an attempt to get some previously announced research noticed by sending out a summary news release using a new ‘hook’ to get attention. I hope it works for them as it must be disheartening to have your research sink into obscurity because the announcements were issued during one or more busy news cycles.

One final note, if I understand the news release correctly, this work is still largely theoretical as there don’t seem to have been any field tests.

Water desalination by graphene and water purification by sapwood

I have two items about water. The first concerns a new technique from MIT (Massachusetts Institute of Technology) for desalination using graphene and sapwood, respectively*. From a Feb. 25, 2014 news release by David Chandler on EurekAlert,

Researchers have devised a way of making tiny holes of controllable size in sheets of graphene, a development that could lead to ultrathin filters for improved desalination or water purification.

The team of researchers at MIT, Oak Ridge National Laboratory, and in Saudi Arabia succeeded in creating subnanoscale pores in a sheet of the one-atom-thick material, which is one of the strongest materials known. …

The concept of using graphene, perforated by nanoscale pores, as a filter in desalination has been proposed and analyzed by other MIT researchers. The new work, led by graduate student Sean O’Hern and associate professor of mechanical engineering Rohit Karnik, is the first step toward actual production of such a graphene filter.

Making these minuscule holes in graphene — a hexagonal array of carbon atoms, like atomic-scale chicken wire — occurs in a two-stage process. First, the graphene is bombarded with gallium ions, which disrupt the carbon bonds. Then, the graphene is etched with an oxidizing solution that reacts strongly with the disrupted bonds — producing a hole at each spot where the gallium ions struck. By controlling how long the graphene sheet is left in the oxidizing solution, the MIT researchers can control the average size of the pores.

A big limitation in existing nanofiltration and reverse-osmosis desalination plants, which use filters to separate salt from seawater, is their low permeability: Water flows very slowly through them. The graphene filters, being much thinner, yet very strong, can sustain a much higher flow. “We’ve developed the first membrane that consists of a high density of subnanometer-scale pores in an atomically thin, single sheet of graphene,” O’Hern says.

For efficient desalination, a membrane must demonstrate “a high rejection rate of salt, yet a high flow rate of water,” he adds. One way of doing that is decreasing the membrane’s thickness, but this quickly renders conventional polymer-based membranes too weak to sustain the water pressure, or too ineffective at rejecting salt, he explains.

With graphene membranes, it becomes simply a matter of controlling the size of the pores, making them “larger than water molecules, but smaller than everything else,” O’Hern says — whether salt, impurities, or particular kinds of biochemical molecules.

The permeability of such graphene filters, according to computer simulations, could be 50 times greater than that of conventional membranes, as demonstrated earlier by a team of MIT researchers led by graduate student David Cohen-Tanugi of the Department of Materials Science and Engineering. But producing such filters with controlled pore sizes has remained a challenge. The new work, O’Hern says, demonstrates a method for actually producing such material with dense concentrations of nanometer-scale holes over large areas.

“We bombard the graphene with gallium ions at high energy,” O’Hern says. “That creates defects in the graphene structure, and these defects are more chemically reactive.” When the material is bathed in a reactive oxidant solution, the oxidant “preferentially attacks the defects,” and etches away many holes of roughly similar size. O’Hern and his co-authors were able to produce a membrane with 5 trillion pores per square centimeter, well suited to use for filtration. “To better understand how small and dense these graphene pores are, if our graphene membrane were to be magnified about a million times, the pores would be less than 1 millimeter in size, spaced about 4 millimeters apart, and span over 38 square miles, an area roughly half the size of Boston,” O’Hern says.

With this technique, the researchers were able to control the filtration properties of a single, centimeter-sized sheet of graphene: Without etching, no salt flowed through the defects formed by gallium ions. With just a little etching, the membranes started allowing positive salt ions to flow through. With further etching, the membranes allowed both positive and negative salt ions to flow through, but blocked the flow of larger organic molecules. With even more etching, the pores were large enough to allow everything to go through.

Scaling up the process to produce useful sheets of the permeable graphene, while maintaining control over the pore sizes, will require further research, O’Hern says.

Karnik says that such membranes, depending on their pore size, could find various applications. Desalination and nanofiltration may be the most demanding, since the membranes required for these plants would be very large. But for other purposes, such as selective filtration of molecules — for example, removal of unreacted reagents from DNA — even the very small filters produced so far might be useful.

“For biofiltration, size or cost are not as critical,” Karnik says. “For those applications, the current scale is suitable.”

Dexter Johnson in a Feb. 26,2014 posting provides some context for and insight into the work (from the Nanoclast blog on the IEEE [Institute of Electrical and Electronics Engineers]), Note: Links have been removed,

About 18 months ago, I wrote about an MIT project in which computer models demonstrated that graphene could act as a filter in the desalination of water through the reverse osmosis (RO) method. RO is slightly less energy intensive than the predominantly used multi-stage-flash process. The hope was that the nanopores of the graphene material would make the RO method even less energy intensive than current versions by making it easier to push the water through the filter membrane.

The models were promising, but other researchers in the field said at the time it was going to be a long road to translate a computer model to a real product.

It would seem that the MIT researchers agreed it was worth the effort and accepted the challenge to go from computer model to a real device as they announced this week that they had developed a method for creating selective pores in graphene that make it suitable for water desalination.

Here’s a link to and a citation for the paper,

Selective Ionic Transport through Tunable Subnanometer Pores in Single-Layer Graphene Membranes by Sean C. O’Hern, Michael S. H. Boutilier, Juan-Carlos Idrobo, Yi Song, Jing Kong, Tahar Laoui, Muataz Atieh, and Rohit Karnik. Nano Lett., Article ASAP DOI: 10.1021/nl404118f Publication Date (Web): February 3, 2014

Copyright © 2014 American Chemical Society

This article is behind a paywall.

The second item is also from MIT and concerns a low-tech means of purifying water. From a Feb. 27, 2014 news item on Azonano,

If you’ve run out of drinking water during a lakeside camping trip, there’s a simple solution: Break off a branch from the nearest pine tree, peel away the bark, and slowly pour lake water through the stick. The improvised filter should trap any bacteria, producing fresh, uncontaminated water.

In fact, an MIT team has discovered that this low-tech filtration system can produce up to four liters of drinking water a day — enough to quench the thirst of a typical person.

In a paper published this week in the journal PLoS ONE, the researchers demonstrate that a small piece of sapwood can filter out more than 99 percent of the bacteria E. coli from water. They say the size of the pores in sapwood — which contains xylem tissue evolved to transport sap up the length of a tree — also allows water through while blocking most types of bacteria.

Co-author Rohit Karnik, an associate professor of mechanical engineering at MIT, says sapwood is a promising, low-cost, and efficient material for water filtration, particularly for rural communities where more advanced filtration systems are not readily accessible.

“Today’s filtration membranes have nanoscale pores that are not something you can manufacture in a garage very easily,” Karnik says. “The idea here is that we don’t need to fabricate a membrane, because it’s easily available. You can just take a piece of wood and make a filter out of it.”

The Feb. 26, 2014 news release on EurekAlert, which originated the news item, describes current filtration techniques and the advantages associated with this new low-tech approach,

There are a number of water-purification technologies on the market today, although many come with drawbacks: Systems that rely on chlorine treatment work well at large scales, but are expensive. Boiling water to remove contaminants requires a great deal of fuel to heat the water. Membrane-based filters, while able to remove microbes, are expensive, require a pump, and can become easily clogged.

Sapwood may offer a low-cost, small-scale alternative. The wood is comprised of xylem, porous tissue that conducts sap from a tree’s roots to its crown through a system of vessels and pores. Each vessel wall is pockmarked with tiny pores called pit membranes, through which sap can essentially hopscotch, flowing from one vessel to another as it feeds structures along a tree’s length. The pores also limit cavitation, a process by which air bubbles can grow and spread in xylem, eventually killing a tree. The xylem’s tiny pores can trap bubbles, preventing them from spreading in the wood.

“Plants have had to figure out how to filter out bubbles but allow easy flow of sap,” Karnik observes. “It’s the same problem with water filtration where we want to filter out microbes but maintain a high flow rate. So it’s a nice coincidence that the problems are similar.”

The news release also describes the experimental procedure the scientists followed (from the news release),

To study sapwood’s water-filtering potential, the researchers collected branches of white pine and stripped off the outer bark. They cut small sections of sapwood measuring about an inch long and half an inch wide, and mounted each in plastic tubing, sealed with epoxy and secured with clamps.

Before experimenting with contaminated water, the group used water mixed with red ink particles ranging from 70 to 500 nanometers in size. After all the liquid passed through, the researchers sliced the sapwood in half lengthwise, and observed that much of the red dye was contained within the very top layers of the wood, while the filtrate, or filtered water, was clear. This experiment showed that sapwood is naturally able to filter out particles bigger than about 70 nanometers.

However, in another experiment, the team found that sapwood was unable to separate out 20-nanometer particles from water, suggesting that there is a limit to the size of particles coniferous sapwood can filter.

Finally, the team flowed inactivated, E. coli-contaminated water through the wood filter. When they examined the xylem under a fluorescent microscope, they saw that bacteria had accumulated around pit membranes in the first few millimeters of the wood. Counting the bacterial cells in the filtered water, the researchers found that the sapwood was able to filter out more than 99 percent of E. coli from water.

Karnik says sapwood likely can filter most types of bacteria, the smallest of which measure about 200 nanometers. However, the filter probably cannot trap most viruses, which are much smaller in size.

The researchers have future plans (from the news release),

Karnik says his group now plans to evaluate the filtering potential of other types of sapwood. In general, flowering trees have smaller pores than coniferous trees, suggesting that they may be able to filter out even smaller particles. However, vessels in flowering trees tend to be much longer, which may be less practical for designing a compact water filter.

Designers interested in using sapwood as a filtering material will also have to find ways to keep the wood damp, or to dry it while retaining the xylem function. In other experiments with dried sapwood, Karnik found that water either did not flow through well, or flowed through cracks, but did not filter out contaminants.

“There’s huge variation between plants,” Karnik says. “There could be much better plants out there that are suitable for this process. Ideally, a filter would be a thin slice of wood you could use for a few days, then throw it away and replace at almost no cost. It’s orders of magnitude cheaper than the high-end membranes on the market today.”

Here’s a link to and a citation for the paper,

Water Filtration Using Plant Xylem by Michael S. H. Boutilier, Jongho Lee, Valerie Chambers, Varsha Venkatesh, & Rohit Karnik. PLOS One Published: February 26, 2014 DOI: 10.1371/journal.pone.0089934

This paper is open access.

One final observation, two of the researchers (Michael S. H. Boutilier & Rohit Karnik) listed as authors on the graphene/water desalination paper are also listed on the low-tech sapwood paper solution.*

* The first sentence of the this post originally stated both items were graphene-related, it has been changed to say 1… using graphene and sapwood, respectively*’ on May 8, 2015.

The last sentence of this post was changed from

‘One final observation, two of the researchers listed as authors on the graphene/water desalination paper are also listed on the low-tech sapwood paper (Michael S. H. Boutilier & Rohit Karnik).’

to this

‘One final observation, two of the researchers (Michael S. H. Boutilier & Rohit Karnik) listed as authors on the graphene/water desalination paper are also listed on the low-tech sapwood paper solution.*’ for clarity on May 8, 2015.

Inventions Nanotech Middle East conference in 2013

It’s a bit early to be talking about this conference since there isn’t much information, no speakers, no programme, etc. but there’s still time to pull that all together since the Inventions Nanotech Middle East Conference (aka, Inventions Nanotech ME) is scheduled for Nov. 3-5, 2013. From the Conference Overview page,

The Conference will host top notch industry experts from all over the world who will address the following crucial topics through live demonstrations and case studies:

Energy / Oil & Gas
Consumer Products

The event will be held at the Qatar National Convention Center.

There are two main sources of nanotech news items in that region. Iran or INIC  (Iran Nanotechnology Initiative Council [my Dec. 27, 2012 posting]), which continuously publicizes its nanotechnology research, and Saudi Arabia (KAUST or King Abdullah University of Science and Technology), which publicizes its work on solar energy (my July 30, 2012 posting), for the most part.

Good luck to the conference organizers.

Hands off the bubbles in my boiling water!

The discovery that boiling water bubbled was important to me. I’ve never really thought about it until now when researchers at Northwestern University have threatened to take my bubbles away, metaphorically speaking. From the Sept. 13, 2012 news item on ScienceDaily,

Every cook knows that boiling water bubbles, right? New research from Northwestern University turns that notion on its head.

“We manipulated what has been known for a long, long time by using the right kind of texture and chemistry to prevent bubbling during boiling,” said Neelesh A. Patankar, professor of mechanical engineering at Northwestern’s McCormick School of Engineering and Applied Science and co-author of the study.

This discovery could help reduce damage to surfaces, prevent bubbling explosions and may someday be used to enhance heat transfer equipment, reduce drag on ships and lead to anti-frost technologies.

The Sept. 13, 2012 news release from McCormick University (which originated the news item) provides details,

This phenomenon is based on the Leidenfrost effect. In 1756 the German scientist Johann Leidenfrost observed that water drops skittered on a sufficiently hot skillet, bouncing across the surface of the skillet on a vapor cushion or film of steam. The vapor film collapses as the surface falls below the Leidenfrost temperature. When the water droplet hits the surface of the skillet, at 100 degrees Celsius, boiling temperature, it bubbles.

To stabilize a Leidenfrost vapor film and prevent bubbling during boiling, Patankar collaborated with Ivan U. Vakarelski of King Abdullah University of Science and Technology, Saudi Arabia. Vakarelski led the experiments and Patankar provided the theory. The collaboration also included Derek Chan, professor of mathematics and statistics from the University of Melbourne in Australia.

In their experiments, the stabilization of the Leidenfrost vapor film was achieved by making the surface of tiny steel spheres very water-repellant. The spheres were sprayed with a commercially available hydrophobic coating — essentially self-assembled nanoparticles — combined with other water-hating chemicals to achieve the right amount of roughness and water repellency. At the correct length scale this coating created a surface texture full of tiny peaks and valleys.

When the steel spheres were heated to 400 degrees Celsius and dropped into room temperature water, water vapors formed in the valleys of the textured surface, creating a stable Leidenfrost vapor film that did not collapse once the spheres cooled to the temperature of boiling water. In the experiments, researchers completely avoided the bubbly phase of boiling.

To contrast, the team also coated tiny steel spheres with a water-loving coating, heated the objects to 700 degrees Celsius, dropped them into room temperature water and observed that the Leidenfrost vapor collapsed with a vigorous release of bubbles.

The scientists have provided a video illustrating their work,

This movie shows the cooling of 20 mm hydrophilic (left) and superhydrophobic (right) steel spheres in 100 C water. The spheres’ initial temperature is about 380 C. The bubbling phase of boiling is completely eliminated for steel spheres with superhydrophobic coating. (from Vimeo, http://vimeo.com/49391913)

I understand there are advantages to not having bubbles in hot water but it somehow seems wrong. I’ve given up a lot over the years: gravity, boundaries between living and non-living (that was a very big thing to give up), and other distinctions that I have made based on traditional science but, today, this is one step too far.

It may seem silly but that memory of my mother explaining that you identify boiling water by its bubbles is important to me. It was one of my first science lessons. I imagine I will recover from this moment but it does remind me of how challenging it can be when your notions of reality/normalcy are challenged by various scientific endeavours. The process can get quite exhausting as you keep recalibrating everything you ‘know’ all the time.

When wrinkles are good for us

I like the video animation that the scientists at the Massachusetts Institute of Technology (MIT) have provided so much (particularly the raisins), I’m going to start with it,

The August 1, 2012 MIT news release on EurekAlert provides some additional detail,

This basic method, they say, could be harnessed for a wide variety of useful structures: microfluidic systems for biological research, sensing and diagnostics; new photonic devices that can control light waves; controllable adhesive surfaces; antireflective coatings; and antifouling surfaces that prevent microbial buildup.

A paper describing this new process, co-authored by MIT postdocs Jie Yin and Jose Luis Yagüe, former student Damien Eggenspieler SM ’10, and professors Mary Boyce and Karen Gleason, is being published in the journal Advanced Materials.

The process uses two layers of material. The bottom layer, or substrate, is a silicon-based polymer that can be stretched, like canvas mounted on a stretcher frame. Then, a second layer of polymeric material is deposited through an initiated chemical vapor deposition (iCVD) process in which the material is heated in a vacuum so that it vaporizes, and then lands on the stretched surface and bonds tightly to it. Then — and this is the key to the new process — the stretching is released first in one direction, and then in the other, rather than all at once.

When the tension is released all at once, the result is a jumbled, chaotic pattern of wrinkles, like the surface of a raisin. But the controlled, stepwise release system developed by the MIT team creates a perfectly orderly herringbone pattern.

The David Chandler Aug.  1, 2012 article (written for MIT) which originated the news release notes,

Many techniques have been used to create surfaces with such tiny patterns, whose dimensions can range from nanometers (billionths of a meter) to tens of micrometers (millionths of a meter). But most such methods require complex fabrication processes, or can only be used for very tiny areas.

The new method is both very simple (consisting of just two or three steps) and can be used to make patterned surfaces of larger sizes, the team says. “You don’t need an external template” to create the pattern, says Yin, the paper’s lead author.

John Hutchinson, a professor of engineering and of applied mechanics at Harvard University who was not involved in this research, says, “Wrinkling phenomena are highly nonlinear and answers to questions concerning pattern formation have been slow to emerge.” He says the MIT team’s work “is an important step forward in this active area of research that bridges the chemical and mechanical engineering communities. The advance rests on theoretical insights combined with experimental demonstration and numerical simulation — it covers all the bases.”

The work was funded by the King Fahd University of Petroleum and Minerals in Saudi Arabia.

It’s nice to see wrinkles being appreciated.

Peter Julian interview on tabling the first nanotechnology bill in Canada’s parliament (part 1 of 3); musings on oil-rich regions and nanotechnology

In mid-March 2010, Member of Parliament, Peter Julian, NDP (New Democrat Party) tabled the first Canadian bill (ETA June 22, 2010: Bill C-494) to regulate nanotechnology. Kudos to him for bringing nanotechnology into a national public forum and hopefully inspiring some discussion and debate.

Mr. Julian kindly agreed (thank you!) to answer some e-mail interview questions which I will be posting in a 3-part interview starting today where he answers questions about why he tabled the bill, the involvement of the NDP’s science shadow minister, and the state of the NDP’s science policy.

For anyone who’s not familiar with Mr. Julian, I got some biographical information from his constituency website,

Peter Julian

Member of Parliament, Burnaby–New Westminster
International Trade
Asia-Pacific Gateway
Deputy Critic Fisheries (West Coast Fisheries)
2010 Olympics

  • Has been the most active MP from Western Canada so far in the 40th Parliament.
  • First elected Member of Parliament for Burnaby-New Westminster in 2004 (by a narrow margin of 300 votes), and re-elected in 2006 (by 4,000 votes) and again in 2008 (by 7,000 votes).
  • Served as Critic on International Trade, Transportation, Persons with Disabilities, Gateways and the Vancouver 2010 Olympics in 39th Parliament; Critic on International Trade, the Treasury Board, Transportation and Persons with Disabilities in 38th Parliament.
  • Ranked fifth of 308 MPs in crafting of Private Member’s legislation in 39th Parliament including tougher drunk driving laws and eliminating toxic substances found in fire retardants.
  • Most active rookie in the House of Commons in the 38th Parliament.
  • Prominent critic of Harper Conservatives’ softwood lumber sellout. Called “the Iron Man” by CTV’s David Akin for determination to stop the sellout.
  • Previously a financial administrator, community activist and manual labourer. Served as National Executive Director of Council of Canadians – (founding member), former Executive Director of the Western Institute for the Deaf and Hard of Hearing (WIDHH).
  • Instrumental in building the British Columbia Disability Employment Network
  • Former National Policy Coordinator and Assistant and Acting Federal Secretary of the New Democratic Party of Canada.

Now on to the interview:

What was the impetus for including nanotechnology as part of this bill? i.e. was there some specific incident or has this been an ongoing concern?

The major forces for including my bill on nanotechnology were; the concerns raised by constituents, the progressive work done by the European Union (including the EU Council Directive on cosmetic products and the January 2010 report of the UK’s House of Lords Science and Technology Committee Report). In contrast Canada has made minimal progress towards ensuring that nanotechnology discoveries are safely introduced into the marketplace, environment, and to Canadians.

The exponential increase in applications and products using this type of technology makes updating the regulatory framework necessary. A regulatory vacuum cannot persist if the commercial and societal promises of nanotechnologies are to be fulfilled. There are trade and safety implications involved.

A modernized regulatory framework, based on precaution given the rapid evolution of nanotechnologies, would help ensure that Canadians will be protected from unintended effects. At the same time, it would enable Canadian businesses to enjoy a predictable regulatory environment for investment and innovation, for nanotechnology is a key driver in Canada’s continued growth via sustainable development.

The following are the key components of Bill C-494:

A) A definition of Nanotechnology definition based on “nanometre scale” (1-1000nm),

B) Prescribed Government of Canada research and studies, with the precautionary principle providing direction for a ‘life-cycle’ approach to nanotechnology, and,

C) A Nanotechnology Inventory established and published.

I believe that the definition contained in Bill C-494 constitutes the first legislative body effort since UK House of Lords Committee recommended a similar nanometre scale definition.

Was the NDP’s science shadow minister involved in this bill? What was Jim Malloway’s contribution?

As you may know, private members bills are at the initiative of individual MPs. I have consulted with the NDP Environment and Health critics, in addition to our own research, library of Parliament support, and input from civil society. Jim Malloway and the NDP caucus support the principle of Bill C-494 and share the view that Nanotechnologies present a tremendous opportunity for Canada and that is why safety must be ensured.

Is there going to be more interest in science policy from the NDP?

The NDP is focused on securing sound foundations for science policy by making sure the government has enough resources to support the development of science while monitoring the consequences. We are also focused on ensuring that funding for post secondary education is appropriate and the resources and knowhow of the public sector are not trivialized and outsourced. The civil service needs a critical mass of expertise to support a healthy science development policy. We must encourage and preserve independent research at the university level and make sure that it is not subservient to corporate funding. Science must be allowed to evolve regardless of the commercial aspect. Our small caucus is focused on helping create these conditions where Canadian science and its applications can flourish in both private and not-for-profit spheres, with appropriate regulatory safeguards.

Tomorrow: Mr. Julian answers questions about the ‘precautionary principle’ and the research that supports his bill.

Peter Julian interview Part 2, Part 3, Comments: Nano Ontario, Comments: nanoAlberta

Oil-rich regions and nano

I had a few idle thoughts on seeing a notice on Nanowerk in mid-March that Iran has published a national nanotechnology standard. From the notice on Nanowerk,

The committee of Iranian nanotechnology standardization chose 49 main words in nanotechnology by means of ISO, BSI, and ASTM published standards and translated their definitions into Persian in cooperation with a team from Persian Language and Literature Academy.

The words like nanotechnology, nanomaterials, nanoparticle, nanoscale, nanotube, nanosystem etc have been defined in this standard.

(I did click on the link for the publication but unfortunately there doesn’t seem to be an English language version available.)

I find it interesting that there is so much activity on the nanotechnology front in Iran and other other oil-producing regions including Alberta (Canada) which hosts the National Institute for Nanotechnology and gets a great deal of funding from the Alberta provincial government. Texas, also known for its oil, hosts a leader in nanotechnology research, Rice University which is celebrating its 25th anniversary as the site where ‘bucky balls’ or buckminster fullerenes were first discovered. In Saudi Arabia, they opened KAUST (King Abdullah University for Science and Technology) in September 2009. While the ambitions range far beyond (the Saudis hope to establish a modern ‘House of Wisdom’) nanotechnology, its research is an important element in the overall scheme of things. I guess the reason that all these areas which are known for their oil production are so invested in nanotechnology is that they know time is running out and they need new ways to keep their economies afloat.

Transatlantic Regulatory Cooperation tidbits; TAPPI and the nanotechnology forestry conference in Alberta; a modern House of Wisdom

I caught only part of the Project on Emerging Nanotechnologies (PEN) event, Transatlantic Regulatory Cooperation, due to two factors. (1) I was busy posting here and so was late to the live webcast. (2) About an hour after I started watching, something (either my system choked or the Wilson Center facility was having difficulties or I lost broadband speed for some reason)  happened and the live webcast became unwatchable.

This was an international collaborative project titled, Regulating Nanotechnologies in the EU and US. Researchers from the London School of Economics and Political Science (LSE), Chatham House, the Environmental Law Institute (ELI), and PEN at the Woodrow Wilson International Center for Scholars worked together to produce a report, a briefing paper, and a slide presentation about their findings and recommendations that can be downloaded from here.

The Washington, DC presentation was yesterday (Sept. 23, 2009) at the Wilson Center facility. There were two panels and I missed the introduction for the first group but I did recognize the moderator, David Rejeski who’s PEN’s executive director. The discussion was about the report and the recommendations.

One of the more interesting bits was the mention of a discrepancy between the UK and EU food industries submissions to some sort of inquiry. The UK representative claimed there are 2 nano type food products on the market (in the UK,  i.e. Europe) while in an earlier meeting elsewhere an EU representative claimed there are 20 such products on the market in Europe. No one was able to explain the discrepancy, which is troubling.

As for the participants in the project, there was general agreement that some sort of regulatory system needs to be developed quickly. Amongst other recommendations:

  1. Voluntary reporting of the use and manufacture of nano materials should be made mandatory.
  2. There should be a ‘technology label’ for food and cosmetic products that contain nanomaterials.
  3. A global approach to nanotechnology regulation that draws together major players such as China and India, as well as many others, needs to be adopted.

There was some mention of Canada at one point. I believe the speaker was referring to an Environment Canada initiative, i.e. a one-time inventory of nanomaterials used in manufacturing products which is mandatory. (I commented on this matter in my Feb. 3, 4, and 6, 2009 postings.) I haven’t heard anything about their progress lately but it is used as an example of a mandatory nanotechnology inventory. Interestingly, they never mention that it is supposed to be one time only.

As for the second panel (moderated by Dr. Andrew Maynard, Chief Science Advisor for PEN), this was oriented to some of the practicalities of introducing nano regulation into current regulatory environments. At least, I think that’s what it was about as things began to malfunction shortly after the introductions.

TAPPI (Technical Association of the Pulp and Paper Industry) held a nanotechnology forestry conference in Alberta this last June. I should have mentioned it at the time but, trite as it is,  better late than never.  From today’s news item about the conference on Nanowerk,

More than 180 nanoscience experts from 12 countries met in June to discuss the potential of nano-enabled biomaterials. Held in Edmonton, AB, Canada, and co-sponsored by TAPPI and the Alberta Ingenuity Fund, the conference revealed developments for revolutionizing paper and wood products, as well as capturing sustainability-focused markets with bionanocomposites and capitalizing on wood-derived nanocrystalline cellulose (NCC) and nanofibrillar cellulose (NFC).

The 2010 conference will be held in Helsinki, Finland.

The House of Wisdom existed from the 9th to 13th centuries CE (common era) in Baghdad. Originally intended as a library whose main purpose was for the translation of books from Persian into Arabic, the House of Wisdom became a centre for the study of the humanities and sciences that was unrivaled in its time. One of its great scholars (Al-Khawarizmi) is known as the ‘father of algebra’. They invented the library catalogue where books were organized according to subjects. Note: I was recently at the oldest library at Trinity College in Dublin and the guide mentioned that those books are organized on the shelves by size, weight, and the colour of their bindings. (I got my information about the House of Wisdom here in Wikipedia and from a Nanowerk Spotlight article by Michael Berger.)

I mention the House of Wisdom because of Berger’s article which uses it as a metaphor to discuss a modern attempt to recreate the ‘house’,  this time, in Saudi Arabia. A new, 36 square kilometer,  science/technology campus/city called the King Abdullah University for Science and Technology (KAUST) opened yesterday on Sept. 23, 2009.

From the article,

Much more than a future elite university, the vision behind KAUST is to create the nucleus of a modern society, free from the strict religious dictates of a conservative Islamic culture, and laying the foundation for a science and technology based society of future generations.

This sounds quite ambitious for a conservative Islamic country that doesn’t have public entertainment facilities such as cinemas or theaters – they are regarded as incompatible with Islam; where most schools have focused on religion much more than on science and other modern knowledge; and where a strict interpretation of Islam imposes many restrictions on women’s daily lives.

This all is supposed to change with mega projects like the $8bn Knowledge Economic City (KEC), the King Abdullah Economic City (KAEC) a $26.6 billion project that will generate more than 500,000 jobs upon completion in 2016; and nearby KAUST, intended to catapult Saudi Arabia’s education system into the 21st century and prepare its society for the time after oil. This move to a knowledge-based society is a top priority for the country – in 2009 alone, 25.7% of Saudi Arabia’s budget has been allocated to educational development.

As an oil-producing country, Saudi Arabia is getting ready for a time when there won’t be any left to pump out of the ground. Do read the article as there’s much more about the facilities which, according to Berger, “… will enable top-notch nanotechnology research.”

It reminds me a little of the situation in Alberta where they are currently trying to extract oil from sand only because the oil that was easy to access is almost gone while heavily investing in emerging advanced technologies such as nanotechnology.