Tag Archives: water

Cyborg bacteria to reduce carbon dioxide

This video is a bit technical but then it is about work being presented to chemists at the American Chemical Society’s (ACS) at the 254th National Meeting & Exposition Aug. 20 -24, 2017,

For a more plain language explanation, there’s an August 22, 2017 ACS news release (also on EurekAlert),

Photosynthesis provides energy for the vast majority of life on Earth. But chlorophyll, the green pigment that plants use to harvest sunlight, is relatively inefficient. To enable humans to capture more of the sun’s energy than natural photosynthesis can, scientists have taught bacteria to cover themselves in tiny, highly efficient solar panels to produce useful compounds.

“Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” says Kelsey K. Sakimoto, Ph.D., who carried out the research in the lab of Peidong Yang, Ph.D. “These nanocrystals are much more efficient than chlorophyll and can be grown at a fraction of the cost of manufactured solar panels.”

Humans increasingly are looking to find alternatives to fossil fuels as sources of energy and feedstocks for chemical production. Many scientists have worked to create artificial photosynthetic systems to generate renewable energy and simple organic chemicals using sunlight. Progress has been made, but the systems are not efficient enough for commercial production of fuels and feedstocks.

Research in Yang’s lab at the University of California, Berkeley, where Sakimoto earned his Ph.D., focuses on harnessing inorganic semiconductors that can capture sunlight to organisms such as bacteria that can then use the energy to produce useful chemicals from carbon dioxide and water. “The thrust of research in my lab is to essentially ‘supercharge’ nonphotosynthetic bacteria by providing them energy in the form of electrons from inorganic semiconductors, like cadmium sulfide, that are efficient light absorbers,” Yang says. “We are now looking for more benign light absorbers than cadmium sulfide to provide bacteria with energy from light.”

Sakimoto worked with a naturally occurring, nonphotosynthetic bacterium, Moorella thermoacetica, which, as part of its normal respiration, produces acetic acid from carbon dioxide (CO2). Acetic acid is a versatile chemical that can be readily upgraded to a number of fuels, polymers, pharmaceuticals and commodity chemicals through complementary, genetically engineered bacteria.

When Sakimoto fed cadmium and the amino acid cysteine, which contains a sulfur atom, to the bacteria, they synthesized cadmium sulfide (CdS) nanoparticles, which function as solar panels on their surfaces. The hybrid organism, M. thermoacetica-CdS, produces acetic acid from CO2, water and light. “Once covered with these tiny solar panels, the bacteria can synthesize food, fuels and plastics, all using solar energy,” Sakimoto says. “These bacteria outperform natural photosynthesis.”

The bacteria operate at an efficiency of more than 80 percent, and the process is self-replicating and self-regenerating, making this a zero-waste technology. “Synthetic biology and the ability to expand the product scope of CO2 reduction will be crucial to poising this technology as a replacement, or one of many replacements, for the petrochemical industry,” Sakimoto says.

So, do the inorganic-biological hybrids have commercial potential? “I sure hope so!” he says. “Many current systems in artificial photosynthesis require solid electrodes, which is a huge cost. Our algal biofuels are much more attractive, as the whole CO2-to-chemical apparatus is self-contained and only requires a big vat out in the sun.” But he points out that the system still requires some tweaking to tune both the semiconductor and the bacteria. He also suggests that it is possible that the hybrid bacteria he created may have some naturally occurring analog. “A future direction, if this phenomenon exists in nature, would be to bioprospect for these organisms and put them to use,” he says.

For more insight into the work, check out Dexter Johnson’s Aug. 22, 2017 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website),

“It’s actually a natural, overlooked feature of their biology,” explains Sakimoto in an e-mail interview with IEEE Spectrum. “This bacterium has a detoxification pathway, meaning if it encounters a toxic metal, like cadmium, it will try to precipitate it out, thereby detoxifying it. So when we introduce cadmium ions into the growth medium in which M. thermoacetica is hanging out, it will convert the amino acid cysteine into sulfide, which precipitates out cadmium as cadmium sulfide. The crystals then assemble and stick onto the bacterium through normal electrostatic interactions.”

I’ve just excerpted one bit, there’s more in Dexter’s posting.

Using a sponge to remove mercury from lake water

I’ve heard of Lake Como in Italy but Como Lake in Minnesota is a new one for me. The Minnesota lake is featured in a March 22, 2017 news item about water and sponges on phys.org,

Mercury is very toxic and can cause long-term health damage, but removing it from water is challenging. To address this growing problem, University of Minnesota College of Food, Agricultural and Natural Sciences (CFANS) Professor Abdennour Abbas and his lab team created a sponge that can absorb mercury from a polluted water source within seconds. Thanks to the application of nanotechnology, the team developed a sponge with outstanding mercury adsorption properties where mercury contaminations can be removed from tap, lake and industrial wastewater to below detectable limits in less than 5 seconds (or around 5 minutes for industrial wastewater). The sponge converts the contamination into a non-toxic complex so it can be disposed of in a landfill after use. The sponge also kills bacterial and fungal microbes.

Think of it this way: If Como Lake in St. Paul was contaminated with mercury at the EPA limit, the sponge needed to remove all of the mercury would be the size of a basketball.

A March 16, 2017 University of Minnesota news release, which originated the news item, explains why this discovery is important for water supplies in the state of Minnesota,

This is an important advancement for the state of Minnesota, as more than two thirds of the waters on Minnesota’s 2004 Impaired Waters List are impaired because of mercury contamination that ranges from 0.27 to 12.43 ng/L (the EPA limit is 2 ng/L). Mercury contamination of lake waters results in mercury accumulation in fish, leading the Minnesota Department of Health to establish fish consumption guidelines. A number of fish species store-bought or caught in Minnesota lakes are not advised for consumption more than once a week or even once a month. In Minnesota’s North Shore, 10 percent of tested newborns had mercury concentrations above the EPA reference dose for methylmercury (the form of mercury found in fish). This means that some pregnant women in the Lake Superior region, and in Minnesota, have mercury exposures that need to be reduced.  In addition, a reduced deposition of mercury is projected to have economic benefits reflected by an annual state willingness-to-pay of $212 million in Minnesota alone.

According to the US-EPA, cutting mercury emissions to the latest established effluent limit standards would result in 130,000 fewer asthma attacks, 4,700 fewer heart attacks, and 11,000 fewer premature deaths each year. That adds up to at least $37 billion to $90 billion in annual monetized benefits annually.

In addition to improving air and water quality, aquatic life and public health, the new technology would have an impact on inspiring new regulations. Technology shapes regulations, which in turn determine the value of the market. The 2015 EPA Mercury and Air Toxics Standards regulation was estimated to cost the industry around of $9.6 billion annually in 2020. The new U of M technology has a potential of bringing this cost down and make it easy for the industry to meet regulatory requirements.

Research by Abbas and his team was funded by the MnDRIVE Global Food Venture, MnDRIVE Environment, and USDA-NIFA. They currently have three patents on this technology. To learn more, visit www.abbaslab.com.

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

A Nanoselenium Sponge for Instantaneous Mercury Removal to Undetectable Levels by Snober Ahmed, John Brockgreitens, Ke Xu, and Abdennour Abbas. Advanced Functional Materials DOI: 10.1002/adfm.201606572 Version of Record online: 6 MAR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

STEM for refugees and disaster relief

Just hours prior to the terrorist bombings in Paris (Friday, Nov. 13, 2015), Tash Reith-Banks published a Nov. 13, 2015 essay (one of a series) in the Guardian about science, technology, engineering, and mathematics (STEM) as those specialties apply to humanitarian aid with a special emphasis on Syrian refugee crisis.

This first essay focuses on how engineering and mathematics are essential when dealing with crises (from Reith-Banks’s Nov. 13, 2015 essay), Note: Links have been removed,

Engineering is a clear starting point: sanitation, shelter and supply lines are all essential in any crisis. As Martin McCann, CEO at RedR, which trains humanitarian NGO workers says: “There is the obvious work in providing water and sanitation and shelter. By shelter, we mean not only shelter or housing for disaster-affected people or refugees, but also structures to store both food and non-food items. Access is always critical, so once again engineers are needed to build roads or in some cases temporary landing strips.”

Emergency structures need to be light and fast to transport and erect, but tend not to be durable. One recent development comes from engineers Peter Brewin and Will Crawford of Concrete Canvas., The pair have developed a rapid-setting concrete-impregnated fabric that requires only air and water to harden into a water-proof, fire-resistant construction. This has been used to create rapidly deployable concrete shelters that can be carried in a bag and set up in an hour.

Here’s what one of the concrete shelters looks like,

A Concrete Canvas shelter. Once erected the structure takes 24 hours to harden, and then can be further insulated with earth or snow if necessary. Photograph: Gareth Phillips/Gareth Phillips for the Guardian

A Concrete Canvas shelter. Once erected the structure takes 24 hours to harden, and then can be further insulated with earth or snow if necessary. Photograph: Gareth Phillips/Gareth Phillips for the Guardian

There are many kinds of crises which can lead to a loss of shelter, access to water and food, and diminished safety and health as Reith-Banks also notes in a passage featuring mathematics (Note: A link has been removed),

Maths might seem a far cry from the sort of practical innovation described above, but of course it’s the root of great logistics. Alistair Clark from the University of the West of England is using advanced mathematical modelling to improve humanitarian supply chains to ensure aid is sent exactly where it is needed. Part of the Newton Mobility scheme, Clark’s project will partner with Brazilian disaster relief agencies and develop ways of modelling everything from landslides to torrential downpours in order to create sophisticated humanitarian supply chains that can rapidly adapt to a range of possible disaster scenarios and changing circumstances.

In a similar vein, Professor Amr Elnashai, founder and co-editor of the Journal of Earthquake Engineering, works in earthquake-hit areas to plan humanitarian relief for future earthquakes. He recently headed a large research and development effort funded by the Federal Emergency Management Agency in the USA (FEMA), to develop a computer model of the impact of earthquakes on the central eight states in the USA. This included social impact, temporary housing allocation, disaster relief, medical and educational care, as well as engineering damage and its economic impact.

Reith-Banks also references nanotechnology (Note: A link has been removed),

… Up to 115 people die every hour in Africa from diseases linked to contaminated drinking water and poor sanitation, particularly in the wake of conflicts and environmental disasters. Dr Askwar Hilonga recently won the Royal Academy of Engineering Africa Prize, which is dedicated to African inventions with the potential to bring major social and economic benefits to the continent. Hilonga has invented a low cost, sand-based water filter. The filter combines nanotechnology with traditional sand-filtering methods to provide safe drinking water without expensive treatment facilities.  …

Dr. Hilonga who is based in Tanzania was featured here in a June 16, 2015 posting about the Royal Academy of Engineering Prize, his research, and his entrepreneurial efforts.

Reith-Banks’s* essay provides a valuable and unexpected perspective on the humanitarian crises which afflict this planet *and I’m looking forward to the rest of the series*.

*’Reith-Banks’s’ replaced ‘This’ and ‘and I’m looking forward to the rest of the series’ was added Nov. 17, 2015 at 1620 hours PST.

Graphene and water (G20 Water commentary)

Tim Harper’s, Chief Executive Officer (CEO) of G2O Water, July 13, 2015 commentary was published on Nanotechnology Now. Harper, a longtime figure in the nanotechnology community (formerly CEO of Cientifica, an emerging technologies consultancy and current member of the World Economic Forum, not unexpectedly focused on water,

In the 2015 World Economic Forum’s Global Risks Report survey participants ranked Water Crises as the biggest of all risks, higher than Weapons of Mass Destruction, Interstate Conflict and the Spread of Infectious Diseases (pandemics). Our dependence on the availability of fresh water is well documented, and the United Nations World Water Development Report 2015 highlights a 40% global shortfall between forecast water demand and available supply within the next fifteen years. Agriculture accounts for much of the demand, up to 90% in most of the world’s least-developed countries, and there is a clear relationship between water availability, health, food production and the potential for civil unrest or interstate conflict.

The looming crisis is not limited to water for drinking or agriculture. Heavy metals from urban pollution are finding their way into the aquatic ecosystem, as are drug residues and nitrates from fertilizer use that can result in massive algal blooms. To date, there has been little to stop this accretion of pollutants and in closed systems such as lakes these pollutants are being concentrated with unknown long term effects.

Ten years ago, following discussions with former Israeli Prime Minister Shimon Peres, I organised a conference in Amsterdam called Nanowater to look at how nanotechnology could address global water issues. [emphasis mine] While the meeting raised many interesting points, and many companies proposed potential solutions, there was little subsequent progress.

Rather than a simple mix of one or two contaminants, most real world water can contain hundreds of different materials, and pollutants like heavy metals may be in the form of metal ions that can be removed, but are equally likely to be bound to other larger pieces of organic matter which cannot be simply filtered through nanopores. In fact the biggest obstacle to using nanotechnology in water treatment is the simple fact that small holes are easily blocked, and susceptibility to fouling means that most nanopore membranes quickly become barriers instead of filters.

Fortunately some recent developments in the ‘wonder material’ graphene may change the economics of water. One of the major challenges in the commercialisation of graphene is the ability to create large areas of defect-free material that would be suitable for displays or electronics, and this is a major research topic in Europe where the European Commission is funding graphene research to the tune of a billion euros. …

Tim goes on to describe some graphene-based solutions including a technology developed at the University of South Carolina, which is also mentioned in a July 16, 2015 G20 Water press release,

Fouling of nano/ultrafiltration membranes in oil/water separation is a longstanding issue and a major economic barrier for their widespread adoption. Currently membranes typically show severe fouling, resulting from the strong adhesion of oil on the membrane surface and/or oil penetration inside the membranes. This greatly degrades their performance and shortens service lifetime as well as increasing the energy usage.

G2O™s bio inspired approach uses graphene oxide (GO) for the fabrication of fully-recoverable membranes for high flux, antifouling oil/water separation via functional and structural mimicking of fish scales. The ultra-thin, amphiphilic, water-locking GO coating mimics the thin mucus layer covering fish scales, while the combination of corrugated GO flakes and intrinsic roughness of the porous supports successfully reproduces the hierarchical roughness of fish scales. Cyclic membrane performance evaluation tests revealed circa 100% membrane recovery by facile surface water flushing, establishing their excellent easy-to-recover capability.

The pore sizes can be tuned to specific applications such as water desalination, oil/water separation, storm water treatment and industrial waste water recovery. By varying the GO concentration in water, GO membranes with different thickness can be easily fabricated via a one-time filtration process.
G2O™s patented graphene oxide technology acts as a functional coating for modifying the surface properties of existing filter media resulting in:
Higher pure water flux;
High fouling resistance;
Excellent mechanical strength;
High chemical stability;
Good thermal stability;
Low cost.

We’re going through a water shortage here in Vancouver, Canada after a long spring season which distinguished itself with a lack of rain and the introduction of a heatwave extending into summer. It is by no means equivalent to the situation in many parts of the world but it does give even those of us who are usually waterlogged some insight into what it means when there isn’t enough water.

For more insight into water crises with a special focus on the Middle East (notice Harper mentioned Israel’s former Prime Minister Shimon Peres in his commentary), I have a Feb. 24, 2014 posting (Water desalination to be researched at Oman’s newly opened Nanotechnology Laboratory at Sultan Qaboos University) and a June 25, 2013 post (Nanotechnology-enabled water resource collaboraton between Israel and Chicago).

You can check out the World Economic Forum’s Outlook on the Global Agenda 2015 here.

The Outlook on the Global Agenda 2015 features an analysis of the Top 10 trends which will preoccupy our experts for the next 12-18 months as well as the key challenges facing the world’s regions, an overview of global leadership and governance, and the emerging issues that will define our future.

G20 Water can be found here.

Water wears away stone at Rice University (Texas, US) and at the University of Bremen (Germany)

I am fascinated by research that focuses on boundaries as does this work from Rice University (Texas, US) and the University of Bremen (Germany) but first a general description of the research from a Dec. 6, 2013 news item on Nanowerk (Note: A link has been removed),

Scientists from Rice University and the University of Bremen’s Center for Marine Environmental Sciences (MARUM) in Germany have combined cutting-edge experimental techniques and computer simulations to find a new way of predicting how water dissolves crystalline structures like those found in natural stone and cement.

In a new study featured on the cover of the Nov. 28 issue of the Journal of Physical Chemistry C (“Kinetic Monte Carlo Simulations of Silicate Dissolution: Model Complexity and Parametrization”), the team found their method was more efficient at predicting the dissolution rates of crystalline structures in water than previous methods. The research could have wide-ranging impacts in diverse areas, including water quality and planning, environmental sustainability, corrosion resistance and cement construction.

The Dec. 5, 2013 Rice University news release, which originated the news item, explains the reasons for the research and delves into the subject of boundaries,

“We need to gain a better understanding of dissolution mechanisms to better predict the fate of certain materials, both in nature and in man-made systems,” said lead investigator Andreas Lüttge, a professor of mineralogy at MARUM and professor emeritus and research professor in Earth science at Rice. His team specializes in studying the thin boundary layer that forms between minerals and fluids.

Boundary layers are ubiquitous in nature; they occur when raindrops fall on stone, water seeps through soil and the ocean meets the sea floor. Scientists and engineers have long been interested in accurately explaining how crystalline materials, including many minerals and stones, interact with and are dissolved by water. Calculations about the rate of these dissolution processes are critical in many fields of science and engineering.

In the new study, Lüttge and lead author Inna Kurganskaya, a research associate in Earth science at Rice, studied dissolution processes using quartz, one of the most common minerals found in nature. Quartz, or silicon dioxide, is a type of silicate, the most abundant group of minerals in Earth’s crust.

At the boundary layer where quartz and water meet, multiple chemical reactions occur. Some of these happen simultaneously and others take place in succession. In the new study, the researchers sought to create a computerized model that could accurately simulate the complex chemistry at the boundary layer.

“The new model simulates the dissolution kinetics at the boundary layer with greater precision than earlier stochastic models operating at the same scale,” Kurganskaya said. “Existing simulations rely on rate constants assigned to a wide range of possible reactions, and as a result, the total material flux from the surface have an inherent variance range — a plus or minus factor that is always there.”

The team used new equipment to achieve increased imaging precision (from the news release),

One reason the team’s simulations more accurately represent real processes is that its models incorporate actual measurements from cutting-edge instruments and from high-tech materials, including glass ceramics and nanomaterials. With a special imaging technique called “vertical scanning interferometry,” which the group at MARUM and Rice helped to develop, the team scanned the crystal surfaces of both minerals and manufactured materials to generate topographic maps with a resolution of a just a few nanometers, or billionths of a meter.

“We found that dissolution rates that were predicted using rate constants were sometimes off by as much as two orders of magnitude,” Lüttge said.

The new method for more precisely predicting dissolution processes could revolutionize the way engineers and scientists make many calculations related to a myriad of things, including the stability of building materials, the longevity of materials used for radioactive waste storage and more, he said.

“Further work is needed to prove the broad utility of the method,” he said. “In the next phase of research, we plan to test our simulations on larger systems and over longer periods.”

One often sees funding information at the end of these types of news releases, which I don’t usually include here but I found this one a bit surprising (this is the first time I’ve seen research supported by a university that has no researchers involved in the work),

The research was supported by the Global Climate and Energy Project at Stanford University

The researchers offered this image to illustrate their work,

The dissolution process of a crystalline structure in water is shown: two bonded SiO4 -- molecules dissolve (top left), a quartz crystal (top right) and the computer-simulated surface of a dissolving crystalline structure (below). CREDIT: MARUM & Rice University

The dissolution process of a crystalline structure in water is shown: two bonded SiO4 — molecules dissolve (top left), a quartz crystal (top right) and the computer-simulated surface of a dissolving crystalline structure (below). CREDIT: MARUM & Rice University

For those who just can’t get enough information, here’s a link to and a citation for the paper,

Kinetic Monte Carlo Simulations of Silicate Dissolution: Model Complexity and Parametrization by Inna Kurganskaya and Andreas Luttge. J. Phys. Chem. C, 2013, 117 (47), pp 24894–24906 DOI: 10.1021/jp408845m Publication Date (Web): October 10, 2013
Copyright © 2013 American Chemical Society

This paper is behind a paywall.

Hydrophobic and hydrophilic for beginners

Anyone who’s interested in biomimicry (mimicking nature, for one reason or another) is likely to come across the terms hydrophobic (e.g. lotus leaves where water beads up into little balls) and hydrophilic, materials where water spreads itself evenly (e.g. desert beetles such as the stenocara are partly hydrophilic).  David L. Chandler at MIT (Massachusetts Institute of Technology) has written a good explanation (H/T phys.org) of these two states and the surface tensions which cause them in his article, Explained: Hydrophobic and hydrophilic; Better understanding of how surfaces attract or repel water could improve everything from power plants to ketchup bottles of July 16, 2013,

Materials with a special affinity for water — those it spreads across, maximizing contact — are known as hydrophilic. Those that naturally repel water, causing droplets to form, are known as hydrophobic. Both classes of materials can have a significant impact on the performance of power plants, electronics, airplane wings and desalination plants, among other technologies, says Kripa Varanasi, an associate professor of mechanical engineering at MIT. Improvements in hydrophilic and hydrophobic surfaces could provide ketchup bottles where the condiment just glides right out, glasses that never fog up, or power plants that wring more electricity from a given amount of fuel.

Hydrophilic and hydrophobic materials are defined by the geometry of water on a flat surface — specifically, the angle between a droplet’s edge and the surface underneath it. This is called the contact angle.

If the droplet spreads, wetting a large area of the surface, then the contact angle is less than 90 degrees and that surface is considered hydrophilic, or water-loving (from the Greek words for water, hydro, and love, philos). But if the droplet forms a sphere that barely touches the surface — like drops of water on a hot griddle — the contact angle is more than 90 degrees, and the surface is hydrophobic, or water-fearing.

I recommend  reading this piece in its entirety if you want find out more about this unexpectedly interesting topic. For those who don’t have the patience to read the whole article or like to augment their reading with videos, there’s the Bouncing Droplets: Superhydrophobic and Superhydrophilic Surfaces video at the Khan Academy. This well-paced  video was produced by MIT’s Bioinstrumentation Laboratory and is suitable for older children and adults.

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

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.

Spain, heritage stone, and nano

Petz Scholtus in a June 21, 2012 posting on the Treehugger website has featured an item about nanotechnology and stone (Note: I have removed a link from the excerpt),

Tecnadis PRS Effect is a water-repellent for facades and historical monuments based on nanoparticles. It is being tested on the Cathedral of Santiago de Compostela to prevent the porous stone from absorbing water and humidity, and hence, to make it last longer. What makes this especially suitable for heritage conservation is the fact that it does not close the pores of the stone but instead, lets it breathe.

Here’s a company demonstration of  water being poured on a stone that has been treated with the product (silent with Spanish language titles),

I last posted about Spain, nanotechnology, and heritage conservation efforts in a June 7, 2011 posting about the murals of the Church of Santos Juanes.

University of Texas at Dallas lab demos cloaking device visible to naked eye

Invisibility cloaks have been everywhere lately and I’ve been getting a little blasé about them but then I saw this Oct. 4, 2011 news item on physorg.com,

Scientists have created a working cloaking device that not only takes advantage of one of nature’s most bizarre phenomenon, but also boasts unique features; it has an ‘on and off’ switch and is best used underwater.

For the first time, I was able to see an invisibility cloak in action, here’s the video,

For the curious here’s how it works (from the Oct. 4, 2011 news release on the Institute of Physics website),

This novel design, presented today, Tuesday 4 September [Tuesday 4 October?], in IOP [Institute of Physics] Publishing’s journal Nanotechnology, makes use of sheets of carbon nanotubes (CNT) – one-molecule-thick sheets of carbon wrapped up into cylindrical tubes.

CNTs have such unique properties, such as having the density of air but the strength of steel, that they have been extensively studied and put forward for numerous applications; however it is their exceptional ability to conduct heat and transfer it to surrounding areas that makes them an ideal material to exploit the so-called “mirage effect”.

The most common example of a mirage is when an observer appears to see pools of water on the ground. This occurs because the air near the ground is a lot warmer than the air higher up, causing lights rays to bend upward towards the viewer’s eye rather than bounce off the surface.

This results in an image of the sky appearing on the ground which the viewer perceives as water actually reflecting the sky; the brain sees this as a more likely occurrence.

Through electrical stimulation, the transparent sheet of highly aligned CNTs can be easily heated to high temperatures. They then have the ability to transfer that heat to its surrounding areas, causing a steep temperature gradient. Just like a mirage, this steep temperature gradient causes the light rays to bend away from the object concealed behind the device, making it appear invisible.

With this method, it is more practical to demonstrate cloaking underwater as all of the apparatus can be contained in a petri dish. It is the ease with which the CNTs can be heated that gives the device its unique ‘on and off’ feature.

Congratulations to Dr. Ali Aliev (lead author) and the rest of the University of Texas at Dallas team!

ETA Oct. 5, 2011: I added the preposition ‘of’ to the title and I’m adding a comment about invisibility cloaks.

Comment: Most of the invisibility cloaks I’ve read about are at the nanoscale which means none of us outside a laboratory could possibly observe the cloak in action. Seeing this video demonstrating an invisibility cloak in the range of visible light and at a macroscale was a dream come true, so to speak.

Cleaning dirty water

Two news items about cleaning dirty water and the Canadian nanotech scene in two days! First, I got news of a Canada-China-India-Israel Roundtable on Sustainable Water Management via Nano- and Emerging Technologies held February 22-23, 2011 in Edmonton, Alberta. [Note: The information about the participant countries is directly from the ISTP website and there is no mention of the US as there is in the following article. This may be due to a late entrance to the event.] From the Feb. 22, 2011 article by Dave Cooper in the Vancouver Sun,

Canada joined hands with four other nations Tuesday in a partnership aimed at harnessing the potential of nanotechnology to improving the world’s water supply.

“Applying advanced technology to the problems of water is a serious issue. This is not a sideshow, it is a fundamental issue,” said Henri Rothschild, CEO of federally backed International Science and Technology Partnerships (ISTP) Canada.

The goal of the participants from Canada, the U.S. [?], China, India and Israel is to discuss “the real opportunities to address these challenges by pooling resources and expertise,” he said, in a spectrum from drinking and waste water to desalinization.

… with plenty of local water research underway to deal with the oilsands, funded by industry and governments, the region is now internationally recognized for its water expertise. “There are a lot of scientists and engineers here who know the subject. It’s leading edge and dealing with some very hard issues,” Rothschild said. “With this roundtable, we are trying to break new ground and create something that takes it to another level, and have it based here in Canada. This is one model under discussion,” he added.

There’s more information about the event on the ISTP roundtable wepage and, for those who are curious about the ISTP itself, here’s a description from their Who We Are page,

STPCanada was incorporated as a not-for-profit organization with the primary objective of strengthening Canada’s science and technology (S&T), business to business relations and ultimately overall economic, trade and political relations. ISTPCanada was selected by the Government of Canada, through the Department of Foreign Affairs and International Trade, to deliver the India, China and Brazil elements of its International Science and Technology Partnerships Program (ISTPP). Reflecting that bilateral S&T agreements are already in place with India and China, funding for these two countries was provided to ISTPCanada in April 2007, with additional funding for Brazil expected in 2008/2009 on completion of a similar bilateral agreement.

I do see the flag for the State of California on the page but it’s  not mentioned as a member of the ISTP. Perhaps they haven’t had time to update the site or they’re not sure how to add the information given that the other members are countries. Also, Brazil which is a member of the ISTP was not at the roundtable.

Getting back to the water, I had no idea the Edmonton region was internationally recognized for its expertise in water.  Meanwhile on the other side of the country, researchers from McGill University have developed a new and inexpensive way to filter water in case of emergencies. From the Feb. 23, 2011 news release,

Disasters such as floods, tsunamis, and earthquakes often result in the spread of diseases like gastroenteritis, giardiasis and even cholera because of an immediate shortage of clean drinking water. Now, chemistry researchers at McGill University have taken a key step towards making a cheap, portable, paper-based filter coated with silver nanoparticles to be used in these emergency settings.

“Silver has been used to clean water for a very long time. The Greeks and Romans kept their water in silver jugs,” says Prof. Derek Gray, from McGill’s Department of Chemistry. But though silver is used to get rid of bacteria in a variety of settings, from bandages to antibacterial socks, no one has used it systematically to clean water before. “It’s because it seems too simple,” affirms Gray.

Prof. Gray’s team, which included graduate student Theresa Dankovich, coated thick (0.5mm) hand-sized sheets of an absorbent porous paper with silver nanoparticles and then poured live bacteria through it. “Viewed in an electron microscope, the paper looks as though there are silver polka dots all over,” says Dankovich, “and the neat thing is that the silver nanoparticles stay on the paper even when the contaminated water goes through.” The results were definitive. Even when the paper contains a small quantity of silver (5.9 mg of silver per dry gram of paper), the filter is able to kill nearly all the bacteria and produce water that meets the standards set by the American Environmental Protection Agency (EPA).

The filter is not envisaged as a routine water purification system, but as a way of providing rapid small-scale assistance in emergency settings. “It works well in the lab,” says Gray, “now we need to improve it and test it in the field.”

This story reminds me of an Aug. 18, 2010  news article by Lin Edwards on physorg.com about ‘nano’ tea bags (excerpted from the article),

Scientists in South Africa have come up with a novel way of purifying water on a small scale using a sachet rather like a tea bag, but instead of imparting flavor to the water, the bag absorbs toxins, filters out and kills bacteria, and cleans the water.

The bag, which fits into the neck of an ordinary water bottle, was developed by scientists at Stellenbosch University in South Africa to help communities with no water purification facilities to clean their water. The bags are made of inexpensive tea bag material but instead of containing tea they contain nano-scale antimicrobial fibers that filter out contaminants and microbes, and granules of activated carbon that kill the bacteria. The nano-fibers are about one hundredth the width of a human hair.

According to researcher Marelize Botes, one sachet can clean a liter of the dirtiest water to about the same water quality of bottled water. Once the bag has been used it is discarded and a new bag is fitted in the neck of the bottle. The discarded bags have no environmental impact as they disintegrate in only a few days and the materials are not toxic to humans.

It’s hard to tell how closely related the research and initiatives are despite the fact that they’re all talking about ‘dirty water’. What I mean is that the water being discussed in the Dave Cooper article is industrial water recycled from sewage and waste, while the McGill researchers and the South African researchers are focused on drinking water that has been contaminated.