Archive for March 2007

Smart thin film membranes adopt properties of guest molecules

March 30, 2007

Consider this Craig Ventor piece  about the new treasure trove of bacteria dna/proteins brought in by Craig Venter’s Institute. Science critics are hailing his work as the biggest deal in ocean going genetics since the Beagle voyages of Charles Darwin.

How would this effect desalination research. It would be helpful if someone in the desalination community tasked the Craig Ventor Institute to keep an eye out for proteins that do desalination work.

Great. So you get some desalination proteins. How do you make them into something useful?

Remember Ventor as you read the article below.

Public release date: 28-Mar-2007

Contact: Susan Trulove
STrulove@vt.edu
540-231-5646
Virginia Tech

http://www.eurekalert.org/pub_releases/2007-03/vt-stf031907.php

Smart thin film membranes adopt properties of guest molecules

Blacksburg, Va., March 28, 2007 — Virginia Tech researchers announced last year that they had created a nanostructured membrane that incorporates DNA base pairs in order to impart molecular recognition and binding ability to the synthetic material. This year they will show for the first time that these new films, membranes, and elastomers are compatible with diverse organic and inorganic molecules and will adopt properties of the guest molecules.

The research is being presented as an invited talk at the 233rd national meeting of the American Chemical Society in Chicago March 25-29.

Chemistry professor Tim Long’s research group, students affiliated with the Macromolecule and Interfaces Institute (MII) at Virginia Tech, and the U.S. Army Research Laboratory created a block copolymer, where different monomers are linked in a sequential manner and form a nanostructured film. They used adenine and thymine nucleotides, two of the four DNA base pairs that recognize each other. Then the researchers experimented with different kinds of guest molecules with complementary hydrogen bonding sites (hydrogen has a low energy attraction to many types of atoms).

The low energy attraction, means the guest molecules are widely dispersed throughout the membrane, which then takes on the properties of the guest molecules. “For example,” said Long, “if the guest molecules have ionic sites (sites with positive and negative charges), you will be able to transfer water through a film because you would have ion channels at the nanoscale. It’s similar to the way a cell membrane works to control the flow of specific ions into a cell. You can create protective clothing – against chemicals – that would still allow water vapor through.”

Salts, as ordinary table salt, are hydrophilic (water loving) and their introduction into a block copolymer template permits the placement of the salts at the nanometer dimension. One can imagine forming of channels of salts that are not visible with the human eye, but act as a roadway for the transport of water molecules.

“The research is synergy at the nanotechnology-biotechnology interface,” Long said.

###

The talk, “Nucleobase-containing triblock copolymers as templates for the dispersion of guest molecules at the nanoscale” (PMSE 423) will be presented at 9:05 a.m. Wednesday, March 28, in McCormick Place South room S505A. Authors are Brian Mather of Albuquerque, a chemical engineering doctoral student in MII; Margaux B. Baker, an undergraduate student from the University of Michigan who studied with Long’s group during summer 2006; Long, and Frederick L. Beyer of the U.S. Army Research Laboratory.

Mather received his undergraduate degree from the University of New Mexico. Learn more about his research at Virginia Tech by visiting www.chem.vt.edu/chem-dept/tlong/Brian.html.


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Mind the gap: New information on the hydrophobic water gap

March 23, 2007

This is useful info to anyone doing membrane research. The key take away is that water molecules keep a distance of one molecule diameter from a water repelling surface. The article is here, as well as below.

Mind the gap: New information on the hydrophobic water gap

Gap between the ordered molecules of a hydrophobic layer and water. The water molecules keep a distance of about one molecular diameter. Credit: Max Planck Institute

Gap between the ordered molecules of a hydrophobic layer and water. The water molecules keep a distance of about one molecular diameter. Credit: Max Planck Institute

Researchers have found a gap between water and a water-repelling surface that can give new insight into the way water and oil separate. By using high-energy X-rays at the ESRF, an international team defined the size and characteristics of this gap. The knowledge of the structure of a hydrophobic interface is important because they are crucial in biological systems, and can give insight in protein folding and stability. The researchers publish their results this week in PNAS Early Online Edition.

The repulsion of water is a phenomenon present in many aspects of our lives. Detergent molecules made up of components attracted to water (hydrophilic) and others that repel it (hydrophobic). Proteins also use the interaction with water to assemble into complexes. However, studying hydrophobic structures and what occurs when they encounter water is not entirely straightforward as it is influenced by certain factors. Early studies of the gap formed between water and a hydrophobic surface did not show a coherent picture.Scientists from the Max Planck Institute for Metals Research (Germany), the University of South Australia (Adelaide) and the ESRF carried out experiments on silicon wafers covered by a water-repulsive layer at the surface. The wafers were then immersed in water by a special cell. Studies of the water structure at the interface of the hydrophobic layer confirmed that a gap is formed between the layer and water and that its size is the diameter of a water molecule, somewhere between 0.1 and 0.5 nanometer. The integrated density deficit at the interface amounts to half a monolayer of water molecules.The scientists did further experiments in order to test the influence of gas, which is naturally present in water, on the hydrophobic water gap. During all their experiments they kept the water ultra clean (unlike water in nature) and they introduced gas into the cell until saturation. The result shows that, contrary to previous reports, gas does not play a role in the structure of water at flat interfaces.

This is the first time that high energy synchrotron X-rays have been used as a tool to measure the properties of this gap. “Some teams have used neutrons, but they didn’t have enough resolution, after all, the gap is extremely small and difficult to track,” explained Harald Reichert, the paper’s corresponding author. Despite the superior quality of the X-ray beam, the experiment was still a challenge: the water-repellent layer on the silicon wafer can survive only 50 seconds under the beam, so measurements had to be completed very quickly.

The next step for the team is to produce porous structures and study the properties of water at confined pore interfaces. “These studies will increase our knowledge of how water behaves in different environments. The structure of water in these environments is still, somewhat a mystery to us, despite the fact that our world is surrounded by water”, declared Reichert.

Source: European Synchrotron Radiation Facility

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New Water Modeling Tool

March 23, 2007

This water modeling tool might be useful:

The first comes from Researchers at the University of Delaware:

Equipped with high-speed computers and the laws of physics, scientists from the University of Delaware and Radboud University in the Netherlands have developed a new method to “flush out” the hidden properties of water–and without the need for painstaking laboratory experiments.

The UD researchers used clusters of Linux computers to perform the large-scale computer calculations required for the research. The study took several months to complete.

The result is a new model — the first that can accurately predict both the properties of a pair of water molecules and of liquid water.

Among its many applications, the research should help scientists better understand water in not only its liquid form, but in other states as well, such as crystalline forms of ice, and water in extreme conditions, including highly reactive “supercritical” water, which is used to remove pollutants in wastewater and recover waste plastic in chemical recycling, Szalewicz said.

The model might also be used to model H2O in solution with Na & Cl. Anyhow, there ought to be a way for desalination researchers to make use of the new modeling tool on request.

The rest of the article can be found here.

Fluid dynamics theory works on nanoscale outside vacuum

March 23, 2007

I mentioned last October at the end of a post that:

Penny Smith, a mathematician at Lehigh University, has posted a paper on the arXiv that purports to solve one of the Clay Foundation Millenium problems, the one about the Navier-Stokes Equation. The paper is here, and Christina Sormani has set up a web-page giving some background and exposition of Smith’s work.

There’s further work here.

Fluid dynamics theory works on nanoscale outside vacuum Discussion at PhysOrgForum

A propane liquid nanobridge breaks up in a nitrogen gas environment. Credit: Georgia TechUzi Landman

A propane liquid nanobridge breaks up in a nitrogen gas environment. Credit: Georgia Tech/Uzi Landman

In 2000, Georgia Tech researchers showed that fluid dynamics theory could be modified to work on the nanoscale, albeit in a vacuum. Now, seven years later they’ve shown that it can be modified to work in the real world, too – that is, outside of a vacuum. The results appear in the February 9 issue of Physical Review Letters.

It’s well-known that small systems are influenced by randomness and noise more than large systems. Because of this, Georgia Tech physicist Uzi Landman reasoned that modifying the Navier-Stokes equations to include stochastic elements – that is give the probability that an event will occur – would allow them to accurately describe the behavior of liquids in the nanoscale regime.

Writing in the August 18, 2006, issue of PRL, Landman and post doctoral fellow Michael Moseler used computer simulation experiments to show that the stochastic Navier-Stokes formulation does work for fluid nanojets and nanobridges in a vacuum. The theoretical predictions of this early work have been confirmed experimentally by a team of European scientists (see the December 13, 2006, issue of Physical Review Letters). Now, Landman and graduate student Wei Kang have discovered that by further modifying the Moseler-Landman stochastic Navier-Stokes equations, they can accurately describe this behavior in a realistic non-vacuous environment.

To read the full article go here.

Nanotube formation captured on video

March 23, 2007

Nanotube formation captured on video. (click here for video)

Nanotube formation captured on video

A Cambridge University-led team of scientists have successfully produced live video footage that shows how carbon nanotubes, more than 10,000 times smaller in diameter than a human hair, form.

The video sequences show nanofibres and nanotubes nucleating around miniscule particles of nickel and are already offering greater insight into how these microscopic structures self-assemble. The films can be viewed on the Cambridge University website.


In particular, the team discovered that the carbon network is guided into tubular shape by a drastic restructuring of the nickel – the catalyst in the process. They were also able to track and time the deposition of the carbon around the nickel.

Carbon nanotubes are new building blocks enabling engineers to improve and further miniaturise everyday electronic devices like computers or mobile phones. At the moment scientists can grow nanotubes but cannot accurately control their structure.

Being able to do so is vital as it is the very structure of a nanotube that dictates its properties. The nano-scale video observations mean that scientists will be able to better understand the nucleation of nanotubes and are therefore an important step on the route towards application.

The two sequences show action taking place in real time on an astonishingly small scale. The difference in size between a single-walled nanotube and a human hair is close to the difference between the same human hair and the Eiffel Tower. The microscopic scale involved has, in the past, made it difficult to understand the growth process.

The team used X-rays produced at a synchrotron (a type of particle accelerator) and a modified high-resolution transmission electron microscope to observe and film a process called catalytic chemical vapour deposition. This is one of several methods of producing nanotubes, and involves the application of a gas containing carbon (in this case acetylene) to minute crystalline droplets referred to as “catalyst islands” (the nickel).

As the gas is applied carbon sticks to the catalyst islands forming layers of graphite. In conditions appropriate to creating nanofibres, the nickel particle was pushed upwards in a series of peristaltic movements as the carbon continued to deposit on its sides. At several points the nickel formed a cap which almost “popped” out of the forming tube, leaving a layer of graphite behind it. This process is called “bambooing”, because the resultant carbon nanofibre is a cylinder containing several cavities, each one separated by one of these graphite layers, similar in form to bamboo. Throughout the whole process, the nickel remained crystalline rather than liquid.

The team then looked at conditions more appropriate to producing single-walled carbon nanotubes, which involved less acetylene. The catalyst is not squeezed upwards. Instead, a cap of carbon formed on the top of the nickel, and gradually extended from it to form a tubular structure. The catalyst island was squeezed and reshaped by this process and was moulded by the carbon forming around it rather than retaining its original form.

Dr Stephan Hofmann, who led the research, said: “In order to reach the full application potential for nanotubes, we need to be able to accurately control their growth first. As a manifestation of the impressive progress of nanometrology, we are actually now able to watch molecular objects grow. This new video footage shows that the catalyst itself remains crystalline but is constantly changing its shape as the carbon network is formed around it.

“We cannot yet solve the problem of not being able to self-assemble carbon nanotubes with well-defined characteristics, but we have discovered that if we are to do so, we need to be mindful not just of the carbon dynamics but the changing shape of the catalyst as well.”

Making Biofuel from Pond Scum with Fresh Water Byproduct

March 16, 2007

According to this CSRwire press release this week–“In-Flight Media has produced an impressive current-event documentary type two-minute video clip for GSPI. The video illustrates a solution to both solving the fuel crisis and global warming crisis simultaneously”–(if you believe in CO2 as the cause of global warming–which I don’t) . “Over 5-million people will view this video on Continental Airline flights during the months of April and May (2007). A preview of this video is presently available for viewing at” http://video.google.com/videoplay?docid=595872956429027619.

I have written several pieces on using desalinising greenhouses for dual use desalination and biodiesal

The article below fleshes out the algae-to-biodiesal angle pretty well. What the article doesn’t mention is that Greenfuels is now running second stage tests in Arizona using “greenhouse-like buildings about 30 feet wide by 500 feet long that will house the algae”. Future algae greenhouses could use Seawater Greenhouse desalination technology. This would be especially appropriate for areas in the southwest that have carbon dioxide producing plants sited above briny aquifers–or areas along the US coasts that use coal to produce electricity. As well, here is an article that says adding hydrogen to biomass — while its being turned into fuel — increases efficiencey significantly. The process is a “hybrid hydrogen-carbon process,” (H2CAR). According to this article the Hydrogen-Augmented Fischer-Tropsch Processes yields More Product, No CO2.

The new approach modifies conventional methods for producing liquid fuels from biomass by adding hydrogen from a “carbon-free” energy source, such as solar or nuclear power, during a step called gasification. Adding hydrogen during this step suppresses the formation of carbon dioxide and increases the efficiency of the process, making it possible to produce three times the volume of biofuels from the same quantity of biomass.

The picture looks like this:

That would increase the output of greenhouses turning algae to biodiesal significantly. (Same goes for thermal depolymerization.) Further, solar panels mentioned here will come onstream next fall at 1/10 current costs to convert sunlight to electricity for electrolysis to produce hydrogen for the process mentioned above.

While this talk is about fuel–it should be mentioned that the by product is… fresh water.

The article below mentions that they expect the algae to yield biodiesal for $50@ barrel. I think those numbers will fall.

January 26, 2007

Making Biofuel from Pond Scum

by Shelley Schlender

Oil-rich plants such as soy may offer a cleaner energy alternative to diesel fuel, but Jim Sears says these food crops can’t meet all our diesel needs. The Colorado-based entrepreneur says, even in America’s bountiful croplands, farmers couldn’t grow enough oilseed crops to meet demand.

“It is about 1,000 times more efficient to produce fuel from algae than it is from an irrigated crop. There’s enough water even in the desert from natural rainfall to support this technology.”

— Jim Sears, Solix Biofuels, Founder
“Right now,” [Sears] points out, “if we were to use all the normal sources we know about, such as canola oil, soy, things like this to make biodiesel, the industry thinks they could make 3.7 billion liters a year. That sounds like a lot, but Americans currently use 227 billion liters of diesel a year.”

Fortunately, Sears says, an unconventional crop could produce 100 times more biodiesel per hectare than either canola or soy. It can thrive in places where other crops can’t grow at all, and it only requires the equivalent of 5 centimeters of rain a year. It’s algae, a small but familiar plant, usually seen as a green scum that forms on ponds or aquarium glass.

To demonstrate his crop’s potential, Sears leads the way inside a former coal-fired electric power plant, now the Engines and Energy Conversion Laboratory at Colorado State University (CSU). CSU and Sears’ small company, Solix Biofuels, have teamed up for this research.

Sears passes a two-story tall engine that may soon be running on his biodiesel, and heads to a quieter room where test batches of algae grow in glass beakers. The water ranges from pale yellow to soft Irish green, thanks to millions of microscopic algae.

Biologist Nick Rancis lifts a favorite specimen. “Here we have a species of green algae that grows in fresh water. As you can see, it grows very high density. You can’t even see through it when you hold it up to the light.” He says this strain produces enormous amounts of fat: up to 50 percent of its body weight. And while producing oil from soy or canola generally requires a three to five-month growing season, some algae are so prolific, over half a batch can be harvested for oil production every day. “They can double or triple overnight,” Rancis says.

For industrial production, the researchers are designing enormous growing troughs, wider than two trucks side by side, as long as a football field, and grouped by the thousands around processing plants. In this way, Sears says, algae could supply all the U.S. diesel power on a fraction of the nation’s farmland, just one percent of the 400 million hectares now under cultivation.

“Actually we wouldn’t have to convert any of our arable land,” [Sears] observes. “We could use desert land to grow this algae. It doesn’t require good soil. Just flat land, carbon dioxide and sunlight.”

Carbon dioxide helps algae grow fast and fat, so the team plans to siphon it from fossil fuel power plant exhaust, which will reduce greenhouse gas emissions. And Sears says there are other ways to get the gas. “It would actually start with biomass such as switch grass or wood, where in some countries are the only type of fuel that they have anyway. In that case, the grass, the trees, the wood is pulling the carbon dioxide out of the air, then we burn it as fuel and feed the carbon dioxide to the algae.”

He stresses that no carbon will be added to the atmosphere during all these energy conversion steps, making biofuel from algae is a truly carbon-neutral technology. “It’s essentially solar powered fuel.”

To conserve water, the growing troughs are sealed. The algae grows under a clear plastic lid that allows in plenty of sunlight, but keeps the water the plants are floating in from evaporating. “It is about 1,000 times more efficient to produce fuel from algae than it is from an irrigated crop,” Sears says. “There’s enough water even in the desert from natural rainfall to support this technology.”

Affordable biodiesel is an important focus of the research team, and Bryan Willson, who directs this Engines and Energy Conversion Lab, says the projections look promising. “We believe the technology could be cost competitive with $50 a barrel oil, which is basically where we are right now. Even last year, we were up to $70 a barrel.”

Because building a vast new production system is an enormous undertaking, Sears predicts that it will be five to ten years before biodiesel from algae becomes commonplace. However, Eric Jarvis, a senior scientist at the National Renewable Energy Lab, cautions that it may take longer. “I wouldn’t expect it to meet a large demand for diesel in that time frame, but I’m hoping to see some good demonstration projects in the next 5 to 10 years.” He adds that in the last two years, interest in developing systems for biodiesel from algae has grown tremendously, and he gets phone calls every week from people trying to get into this area.

Whether it takes five years, a decade or a little longer, Jim Sears says he’s certain that biodiesel from algae will become commonplace. He calls it “by far the most scalable and reasonable way to make biofuels in the future in an endlessly sustainable method.”

As he considers that future, a train whistle sounds in the distance. “That train is the train that used to bring the coal to this power plant,” he comments, adding “it is one of the future customers.”

The National Renewable Energy Lab plans to step up their development of biodiesel from algae within the year, and they estimates that along with Colorado State and Solix Biofuels, roughly a dozen other groups around the world are developing similar projects, increasing the likelihood that someday soon, clean-burning algae biodiesel will be the fuel of choice for trucks, boats . . . and trains.

Hydrogen Catalyst Tools at Argonne For Desalination

March 9, 2007

imho there should be a desal lab in the USA working on desalination catalysts. If there isn’t one — then a couple scientists should be funded. The tools they would use are being developed for hydrogen catalysts over at Argonne Labs. Notice how the article below mentions how their tools & methodologies can be applied to other things beside hydrogen catalysts. Read the piece and consider: aren’t the issues here similiar to those of desalination and wouldn’t it be nice to develop a catalyst that would just settle the salt out of solution or make the Na & Cl ions bind so they can’t pass through a semi permiable membrane? Anyhow here’s the article:

 
New nanoscale engineering breakthrough points to hydrogen-powered vehicles

High-resolution transmission electron micrograph that reveals the possibility of platinum skin formation on nanoscale surfaces. Credit: Argonne National Laboratory

High-resolution transmission electron micrograph that reveals the possibility of platinum skin formation on nanoscale surfaces. Credit: Argonne National Laboratory


Researchers at the U.S. Department of Energy’s Argonne National Laboratory have developed an advanced concept in nanoscale catalyst engineering – a combination of experiments and simulations that will bring polymer electrolyte membrane fuel cells for hydrogen-powered vehicles closer to massive commercialization.

The results of their findings identify a clear trend in the behavior of extended and nanoscale surfaces of platinum-bimetallic alloy. Additionally, the techniques and concepts derived from the research program are expected to make overarching contributions to other areas of science well beyond the focus on electrocatalysis.

The Argonne researchers, Nenad Markovic and Vojislav Stamenkovic, published related results last month in Science and this month in Nature Materials on the behavior of single crystal and polycrystalline platinum alloy surfaces. The researchers discovered that the nanosegregated platinum-nickel alloy surface has unique catalytic properties, opening up important new directions for the development of active and stable practical cathode catalysts in fuel cells.

These scientific accomplishments together provide a solid foundation for the development of hydrogen-powered vehicles, as basic research brings value of society today by helping to lay the foundation for tomorrow’s technological breakthroughs. “Understanding catalysis is a grand challenge of nanoscience that is now coming within reach,” said George Crabtree, director of Argonne’s Materials Science Division. “The systematic work that Voya and Nenad are doing is a major step toward transforming catalysis from an empirical art to a fundamental science.”

Their experiments and approach sought to substantially improve and reduce platinum loading as the oxygen-reduction catalyst. The research identified a fundamental relationship in electrocatalytic trends on surfaces between the experimentally determined surface electronic structure (the d -band centre) and activity for the oxygen-reduction reaction. This relationship exhibits “volcano-type” behavior, where the maximum catalytic activity is governed by a balance between adsorption energies of reactive intermediates and surface coverage by spectator (blocking) species.

The electrocatalytic trends established for extended surfaces explain the activity pattern of nanocatalysts and provide a fundamental basis for the enhancement of cathode catalysts. By combining experiments with simulations in the quest for surfaces with desired activity, the researchers developed an advanced concept in nanoscale catalyst engineering.

“In the past, theoretical connections have been suggested between electronic behavior and catalytic activity,” explained Markovic. “Our work represents the first time that the connections have been identified experimentally. For us, this development constitutes the beginning of more breakthrough advances in nanocatalysts.”

According to Stamenkovic, “Our study demonstrates the potential of new analytical tools for characterizing nanoscale surfaces in order to fine tune their properties in a desired direction. We have identified a cathode surface that is capable of achieving and even exceeding the target for catalytic activity with improved stability. This discovery sets a new bar for catalytic activity of the cathodic reaction in fuel cells.”

Through continued research combining nanoscale fabrication, electrochemical characterization and numerical simulation a new generation of multi-metallic systems with engineered nanoscale surfaces is on the horizon. Argonne’s Center for Nanoscale Materials, Advanced Photon Source and Electron Microscopy Center will enable some of this research.

“We have got crucial support from Argonne management to set up the new labs and launch research directions, which would establish Argonne as a leading center in basic sciences related to energy conversion.” said Stamenkovic.

Their lab includes a custom built three-chamber UHV system equipped with the state-of-the-art surface sensitive tools, including Low Energy Ion Scattering Spectroscopy (LEISS), Auger Electron Spectroscopy (AES), angle resolved X-ray photoemission spectroscopy (XPS with monochromator), ultraviolet photoelectron spectroscopy (UPS), Low Energy Electron Diffraction (LEED) optics, sputtering guns, thermal evaporators, dual hemispherical analyzers, and chamber with scanning tunneling microscopy (STM) and atomic force microscopy AFM. All three chambers are connected to each other but they can also work as independent chambers, making it possible to transfer samples from one to the other unit in order to get detailed surface characterization or to make desirable surface modification.

“We hope that this research program will lead the nation to more secure energy independence and a cleaner environment for future generations,” Markovic said.

Source: Argonne National Laboratory

 
 
 

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