Silver ionic liquids are powerful solvents for oil industry

The separation of olefins and paraffin, two hydrocarbon compounds in petroleum waste streams, is a heavy expense for the petrochemical industry. The existing technology consumes a lot of energy because the olefin-paraffin pairs have similar boiling and evaporation properties, making it difficult and costly to separate them. Companies are looking for techniques that reduce energy consumption and that economically recycle such waste streams.

New research at Oak Ridge National Laboratory shows that olefins can be separated from paraffin efficiently and economically using silver complex-based ionic liquids. Room temperature ionic liquids are a promising class of novel materials—salts that are molten at or near room temperature. They are made up of ions rather than molecules. Ionic liquids do not easily evaporate, making them potentially recyclable and environmentally friendly solvents.

There are more than 400 ionic liquids that have been commercialized. The wide variety of materials that can be used to make them enables scientists to choose the ones best suited for a research project. These materials have a wide range of potential applications in the chemical industry, including in the separation of petroleum by-products in the oil industry.

This work builds on recent investigations into a membrane technology that makes it easier to transport olefins out of a waste stream. In this hybrid olefin-paraffin separation method, silver or copper ions are used to bind to olefin to form an ionic liquid. The silver or copper ions then act as carriers for the unwanted and transfer them through the membranes. Two of this new class of silver compound ionic liquids are currently under study.

To get a better understanding of these silver compound ionic liquids, scientists used quasielastic neutron scattering, or QENS, on BASIS, the Backscattering Spectrometer at ORNL's Spallation Neutron Source. QENS can probe the diffusion dynamics at the microscale that characterize these new solvents. Subsequent analysis of the scattering data points to three distinct components in the mechanism that transports the olefins.

The room-temperature ionic liquids for separating petroleum by-products have low vapor pressure (they evaporate only at very high temperatures), high thermal stability, and both positive and negative ions move freely through them. The researchers investigated the usefulness of these metal bearing solvents for the extraction and membrane separation of inorganic, organic, and gaseous species; for sensing volatile organic vapors; and for synthesizing novel materials.

A key feature of these new solvents is that the silver ions are incorporated as integral components of the ionic liquid at the molecular level. They are very stable and the silver content is several orders of magnitude higher than that of conventional liquid- or polymer-supported membranes, which makes it easier to drive the olefins through the membrane. In the current work, QENS neutron scattering provides fundamental insight into the olefin transport that cannot be obtained through other characterization techniques.

The QENS analysis shows that in the temperature range of 300 to 340 K, three dynamic components are present in the silver compound ionic liquid solvents and can be described in the microscopic transport on the pico- to nanosecond timescale. These occur in both the new solvents. The findings are similar to those found in a study of an ionic liquid developed earlier. This suggests that the three dynamic components found by neutron scattering may be a common feature of the ionic liquids' microscopic dynamics and are likely related to a fundamental lack of order in these materials at the nanoscale.

Provided by Oak Ridge National Laboratory (news : web)

Cancer on the breath? The nose knows

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Prof. Hossam Haick

A breath test for "sniffing out" cancer in a person's breath is a step closer to reality, according to a study recently published in the British Journal of Cancer. The study results show that the device developed by Prof. Hossam Haick of the Technion Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute can identify chemical signals in the breath of cancer patients even those with difficult-to-detect head-and-neck cancer.

The Nanoscale Artifical Nose (NA-NOSE), as the device is called, consists of five gold nanoparticle sensors linked to software capable of detecting patterns of molecules inherent in people with cancer. Prof. Haick and his team hope that such a test could one day be used by general practitioners to provide instant cancer diagnoses.

"There's an urgent need to develop new ways to detect head-and-neck cancer because diagnosis of the disease is complicated, requiring specialist examinations,” said Prof. Haick. “We've shown that a simple 'breath test' can spot the patterns of molecules which are found in head-and-neck patients in a small, early study.”  Next up, he says, is testing these results in larger studies to determine if it could lead to a potential screening method for the disease.
More than 80 volunteers took part in the study, 22 of whom had various head-and-neck cancers, 24 of whom had lung cancer, and 36 who were healthy.  In previous tests, the NA-NOSE was also able to detect lung cancer and kidney diseases.
According to American Cancer Society statistics, there were 35,720 new cases of head-and-neck cancer (including cancers of the eye, mouth, voice box and food pipe) in the U.S. in 2009. 

Provided by American Technion Society

Study unlocks secrets of plague with stunning new imaging techniques

Researchers at Sandia National Laboratories have developed a super-resolution microscopy technique that is answering long-held questions about exactly how and why a cell's defenses fail against some invaders, such as plague, while successfully fending off others like E.coli. The approach is revealing never-before-seen detail of the cell membrane, which could open doors to new diagnostic, prevention and treatment techniques.

"We're trying to do molecular biology with a microscope, but in order to do that, we must be able to look at things on a molecular scale," says Jesse Aaron, postdoctoral appointee at Sandia Labs.

The cell membrane is a bustling hub of activity on a miniscule scale. While providing structure and housing the cell's interior, the membrane regulates movement of materials in and out of the cell, controls adhesion to other objects and coordinates the cell's communications and subsequent actions through signaling. Receptor proteins on the surface of immune cells, known as toll-like receptors (TLRs), are tasked with recognizing intruders, or antigens. The TLR4 member of this receptor family responds to certain types of bacteria by detecting lipopolysaccharides (LPS) present on their surface. TLR4 proteins then alert the cell and activate an immune response.

Using imaging techniques they developed, Sandia researchers Aaron, Jeri Timlin and Bryan Carson discovered that TLR4 proteins cluster in the membrane when confronted with LPS derived from E.coli, which increases cell signaling and response. Interestingly, LPS derived from the bacteria that cause plague, Yersinia pestis, do not cause the same effects. This could explain why some pathogens are able to thwart the human immune system.

The plague studies marked the first time such small events have been imaged and compared, the Sandia researchers said. Previously, even the most sophisticated optical microscopes could not image the cell surface with enough spatial resolution to see the earliest binding events, due to the diffraction barrier, which limits what can be resolved using visible light.

"With more traditional visualization methods, you can't see the level of detail you need. It's important to look at not only what's present, but also when and where it's present in the cell," Timlin said.

The technique used by Timlin and Aaron builds on superresolution capabilities developed in recent years, but goes another step by adding dual-color capabilities to the relatively new stochastic optical reconstruction microscopy, or STORM. The combination enables the Sandia team to get a more complete picture by simultaneously imaging LPS and TLR4 receptors on the membrane.

"Current light microscopy capabilities are akin to looking out the window of an airplane and seeing the irrigation circles. You know that plants are there, but you can't tell what kinds of plants they are or what shape the leaves are," said Carson, a Sandia immunologist who was an integral part of the project. "But with this technology, it's like zooming in and seeing the leaves and the structure of the plants. That buys you a lot in terms of understanding what's happening within a cell and specifically how the proteins involved interact."

 

In 2009, the National Institutes of Health awarded Timlin a five-year, $300,000-a-year innovation grant. Next on the team's agenda is developing the capability to image live cells in real time using spectral Stimulated Emission Depletion, or STED. "We're working toward using a version of superresolution that's much more live-cell friendly, and extending that in terms of what colors are available to do multiple colors, while maintaining the live-cell friendliness. I see this as a beginning of a long development in this type of imaging technology," Timlin said.

Potential applications likely will expand as the technology reveals previously unattainable details of cell signaling. Eventually, the Sandia team would like to be able to visualize protein/protein interactions.

"Every biological process that goes on in your body is somehow controlled by proteins forming complexes with other proteins or complexes in the membrane, so this would give you this ability to look, with high spatial resolution and multiplexed color capabilities, at four or more things in a living cell, which can't be done very easily right now. It can be done in pieces, but we want to see the whole biological process," Timlin said.

The technology has exciting potential in immunology and drug discovery. Improved imaging could show the mechanisms viruses use to invade cells, which might lead to drugs that would block entry. "We're hoping to do something like label the viral particles and watch them in real time, or as close as we can to real time, in the internalization process," Carson said. "With the superresolution technique, we can actually watch them move through the membrane and see if there are other structures being recruited by the virus to the site of internalization."

Sandia originally developed the technology in support of its biological national security programs, but the team wants to expand the technology into other areas such as biofuels to better understand where and when different pigments are located on the membrane of oil-producing algae. This would provide valuable insight into their photosynthesis functions, which could lead to more efficient biofuel production.

"A lot of this work is in its early stages, but we're encouraged by what we're seeing and excited about its future potential," Aaron said.

Provided by Sandia National Laboratories (news : web)

Artificial tissue promotes skin growth in wounds

Top left, a tissue scaffold with pores visible. Clockwise, schematic diagrams showing cross-sections microstructured tissue templates. Image: Ying Zheng

(PhysOrg.com) -- Victims of third-degree burns and other traumatic injuries endure pain, disfigurement, invasive surgeries and a long time waiting for skin to grow back. Improved tissue grafts designed by Cornell scientists that promote vascular growth could hasten healing, encourage healthy skin to invade the wounded area and reduce the need for surgeries.

These so-called dermal templates were engineered in the lab of Abraham Stroock, associate professor of chemical and biomolecular engineering at Cornell and member of the Kavli Institute at Cornell for Nanoscale Science, in collaboration with Dr. Jason A. Spector, assistant professor of surgery at Weill Cornell Medical College, and an interdisciplinary team of Ithaca and Weill scientists. The research was published online May 6 in the journal Biomaterials.

The biomaterials are composed of experimental tissue scaffolds that are about the size of a dime and have the consistency of tofu. They are made of a material called type 1 collagen, which is a well-regulated biomaterial used often in surgeries and other biomedical applications. The templates were fabricated with tools at the Cornell NanoScale Science and Technology Facility to contain networks of microchannels that promote and direct growth of healthy tissue into wound sites.

"The challenge was how to promote vascular growth and to keep this newly forming tissue alive and healthy as it heals and becomes integrated into the host," Stroock said.

The grafts promote the ingrowth of a vascular system -- the network of vessels that carry blood and circulate fluid through the body -- to the wounded area by providing a template for growth of both the tissue (dermis, the deepest layer of skin), and the vessels. Type I collagen is biocompatible and contains no living cells itself, reducing concerns about immune system response and rejection of the template.

A key finding of the study is that the healing process responds strongly to the geometry of the microchannels within the collagen. Healthy tissue and vessels can be guided to grow toward the wound in an organized and rapid manner.

Dermal templates are not new; the Johnson & Johnson product Integra, for example, is widely used for burns and other deep wounds, Spector said, but it falls short in its ability to encourage growth of healthy tissue because it lacks the microchannels designed by the Cornell researchers.

"They can take a long time to incorporate into the person you're putting them in," Spector said. "When you're putting a piece of material on a patient and the wound is acellular, it has a big risk for infection and requires lots of dressing changes and care. Ideally you want to have a product or material that gets vascularized very rapidly."

In the clinic, Spector continued, patients often need significant reconstructive surgery to repair injuries with exposed vital structures like bone, tendon or orthopedic hardware. The experimental templates are specifically designed to improve vascularization over these "barren" areas, perhaps one day eliminating the need for such invasive surgeries and reducing the patient's discomfort and healing time.

Eventually, the scientists may try to improve their tissue grafts by, for example, reinforcing them with polymer meshes that could also act as a wound covering, Spector said.

Other collaborators include first author Ying Zheng, a former postdoctoral associate in Stroock's lab; Dr. Peter W. Henderson, chief research fellow at Weill Cornell's Laboratory for Bioregenerative Medicine and Surgery; graduate student Nak Won Choi; and Lawrence J. Bonassar, associate professor of biomedical engineering.

Provided by Cornell University (news : web)

Splitting water to create renewable energy simpler than first thought?

An international team, of scientists, led by a team at Monash University has found the key to the hydrogen economy could come from a very simple mineral, commonly seen as a black stain on rocks.

Their findings, developed with the assistance of researchers at UC Davis in the USA and using the facilities at the Australian Synchrotron, was published in the journal Nature Chemistry yesterday 15 May 2011.

Professor Leone Spiccia from the School of Chemistry at Monash University said the ultimate goal of researchers in this area is to create a cheap, efficient way to split water, powered by sunlight, which would open up production of hydrogen as a clean fuel, and leading to long-term solutions for our renewable energy crisis.

To achieve this, they have been studying complex catalysts designed to mimic the catalysts plants use to split water with sunlight. But the new study shows that there might be much simpler alternatives to hand.

“The hardest part about turning water into fuel is splitting water into hydrogen and oxygen, but the team at Monash seems to have uncovered the process, developing a water-splitting cell based on a manganese-based catalyst," Professor Spiccia said.

"Birnessite, it turns out, is what does the work. Like other elements in the middle of the Periodic Table, manganese can exist in a number of what chemists call oxidation states. These correspond to the number of oxygen atoms with which a metal atom could be combined," Professor Spiccia said.

"When an electrical voltage is applied to the cell, it splits water into hydrogen and oxygen and when the researchers carefully examined the catalyst as it was working, using advanced spectroscopic methods they found that it had decomposed into a much simpler material called birnessite, well-known to geologists as a black stain on many rocks."

The manganese in the catalyst cycles between two oxidation states. First, the voltage is applied to oxidize from the manganese-II state to manganese-IV state in birnessite. Then in sunlight, birnessite goes back to the manganese-II State.

This cycling process is responsible for the oxidation of water to produce oxygen gas, protons and electrons.

Co-author on the research paper was Dr Rosalie Hocking, Research Fellow in the Australian Centre for Electromaterials Science who explained that what was interesting was the operation of the catalyst, which follows closely natures biogeochemical cycling of manganese in the oceans.

"This may provide important insights into the evolution of Nature’s water splitting catalyst found in all plants which uses manganese centres,” Dr Hocking said.

“Scientists have put huge efforts into making very complicated manganese molecules to copy plants, but it turns out that they convert to a very common material found in the Earth, a material sufficiently robust to survive tough use.”

The reaction has two steps. First, two molecules of water are oxidized to form one molecule of oxygen gas (O2), four positively-charged hydrogen nuclei (protons) and four electrons. Second, the protons and electrons combine to form two molecules of hydrogen gas (H2).

The experimental work was conducted using state-of-the art equipment at three major facilities including the Australian Synchrotron, the Australian National Beam-line Facility in Japan and the Monash Centre for Electron Microscopy, and involved collaboration with Professor Bill Casey, a geochemist at UC Davis.

"The research highlights the insight obtainable from the synchrotron based spectroscopic techniques – without them the important discovery linking common earth materials to water oxidation catalysts would not have been made," Dr Hocking said.

It is hoped the research will ultimately lead to the development of cheaper devices, which produce hydrogen.

Provided by Monash University (news : web)

Third of tested plastic products found to leach toxic substances in Swedish study

ScienceDaily (May 16, 2011) — Many plastic products contain hazardous chemicals that can leach to the surroundings. In studies conducted at the University of Gothenburg, a third of the tested plastic products released toxic substances, including 5 out of 13 products intended for children.

"Considering how common plastic products are, how quickly the production of plastic has increased and the amount of chemicals that humans and the environment are exposed to, it is important to replace the most hazardous substances in plastic products with less hazardous alternatives," says Delilah Lithner of the Department of Plant and Environmental Sciences at the University of Gothenburg.

Plastics exist in many different chemical compositions and are widespread in the society and the environment. Global annual production of plastics has doubled over the past 15 years, to 245 million tonnes in 2008. The plastic polymers are not regarded as toxic, but there may be toxic residual chemicals, chemical additives and degradation products in the plastic products that can leach out as they are not bound to the plastic polymer. Plastics also cause many waste problems.

In her research, Lithner studied the toxicity of 83 randomly selected plastic products and synthetic textiles. The newly purchased products were leached in pure (deionised) water for 1-3 days. The acute toxicity of the water was then tested using water fleas (Daphnia magna).

"A third of all the 83 plastic products and synthetic chemicals that were tested released substances that were acutely toxic to the water fleas, despite the leaching being mild. Five out of 13 products that were intended for children were toxic, for example bath toys and buoyancy aids such as inflatable armbands," says Delilah Lithner.

The products that resulted in toxic water were soft to semi-soft products made from plasticised PVC or polyurethane, as well as epoxy products and textiles made from various plastic fibres. The toxicity was mainly caused by fat-soluble organic substances.

Lithner also studied the chemicals used to make around 50 different plastic polymers and has identified the plastic polymers for which the most hazardous chemicals are used. They were then ranked on the basis of the environmental and health hazard classifications that exist for the chemicals. Examples of plastic polymers made from the most hazardous chemicals are certain polyurethanes, polyacrylonitriles, PVC, epoxy and certain styrene copolymers. The results are of great benefit for further assessing environmental and health risks associated with plastic materials.

The thesis Environmental and health hazards of chemicals in plastic polymers and products was successfully defended in public on 6th May 2011.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Gothenburg, via EurekAlert!, a service of AAAS.

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