Storing gas in vegetables

A team led by the University of Liverpool and South China University of Technology is investigating the viability of storing gas in ‘bioclathrates’ formed from fungi and vegetables.

Gas storage, both short and long term, is an expensive and energy intensive process, with liquefaction and compression into porous sorbents the two methods under consideration.

Inspired by biomimetic approach
But Professor Andrew Cooper, from the University’s Department of Chemistry, and Weixing
Wang, from South China University of Technology, inspired by the biomimetic approaches to heavy metal storage and the ability of natural structures to facilitate gas transport, decided to delve deeper.

Clathrate hydrates are a chemical compound of water and gas, where the gas molecules are trapped inside a crystalline cage of ordered, hydrogen bonded water molecules. They can form with a large number of low molecular weight gases, such as methane and CO2. But they form very slowly, with high pressures required to force the gas into the water, and low temperatures to form the ice-like structures, making it debatable that the process is more energy efficient than other methods.

Professor Cooper and his team decided to investigate the ability of biological structures, such as fungi and vegetables, to increase the formation rate of clathrate storage without introducing complex mixing technologies.

Mushrooms and aubergines

They found that different biological structures offer significantly varied levels of gas uptake. Mushrooms and aubergines(also known as eggplants) showed most potential, while tomatoes were unable to achieve clathrate formation.

Prof Andy Cooper said: “Clearly, it would not be desirable to use high-value food materials for gas transport, but there might be abundant, non-food biomass that can do the same job. This work is currently a long way from practical application, but we hope that it will inspire other scientists to think about this problem in new ways. There is an enormous variety of biomass on the planet, we limited our initial search to the local supermarket.”

Mining Ancient Ores for Clues to Early Life

An analysis of sulfide ore deposits from one of the world’s richest base-metal mines confirms that oxygen levels were extremely low on Earth 2.7 billion years ago, but also shows that microbes were actively feeding on sulfate in the ocean and influencing seawater chemistry during that geological time period.

The research, reported by a team of Canadian and U.S. scientists in Nature Geoscience, provides new insight into how ancient metal-ore deposits can be used to better understand the chemistry of the ancient oceans — and the early evolution of life.

Sulfate is the second most abundant dissolved ion in the oceans today. It comes from the “rusting” of rocks by atmospheric oxygen, which creates sulfate through chemical reactions with pyrite, the iron sulfide material known as “fool’s gold.”
The researchers, led by PhD student John Jamieson of the University of Ottawa and Prof. Boswell Wing of McGill, measured the “weight” of sulfur in samples of massive sulfide ore from the Kidd Creek copper-zinc mine in Timmins, Ontario, using a highly sensitive instrument known as a mass spectrometer. The weight is determined by the different amounts of isotopes of sulfur in a sample, and the abundance of different isotopes indicates how much seawater sulfate was incorporated into the massive sulfide ore that formed at the bottom of ancient oceans. That ancient ore is now found on Earth’s surface, and is particularly common in the Canadian shield.

The scientists found that much less sulfate was incorporated into the 2.7 billion-year-old ore at Kidd Creek than is incorporated into similar ore forming at the bottom of oceans today. From these measurements, the researchers were able to model how much sulfate must have been present in the ancient seawater. Their conclusion: sulfate levels were about 350 times lower than in today’s ocean. Though they were extremely low, sulfate levels in the ancient ocean still supported an active global population of microbes that use sulfate to gain energy from organic carbon.

“The iron sulfide ore deposits that we looked at are widespread on Earth, with Canada and Quebec holding the majority of them,” says Wing, an associate professor in McGill’s Department of Earth and Planetary Science. “We now have a tool for probing when and where these microbes actually came into global prominence.”

“Deep within a copper-zinc mine in northern Ontario that was once a volcanically active ancient seafloor may not be the most intuitive place one would think to look for clues into the conditions in which the earliest microbes thrived over 2.7 billion years ago,” Jamieson adds. “However, our increasing understanding of these ancient environments and our abilities to analyze samples to a very high precision has opened the door to further our understanding of the conditions under which life evolved.”

Greenland Ice Sheet Carries Evidence of Increased Atmospheric Acidity

Research has shown a decrease in levels of the isotope nitrogen-15 in core samples from Greenland ice starting around the time of the Industrial Revolution. The decrease has been attributed to a corresponding increase in nitrates associated with the burning of fossil fuels.

However, new University of Washington research suggests that the decline in nitrogen-15 is more directly related to increased acidity in the atmosphere.
The increased acidity can be traced to sulfur dioxide, which in the atmosphere is transformed to sulfuric acid, said Lei Geng, a UW research associate in atmospheric sciences. Following the Industrial Revolution, sulfur dioxide emissions increased steadily because of coal burning.

“It changes the chemical properties of the lower troposphere, where we live, and that can have a lot of consequences,” Geng said. He presented his findings on Dec. 7 at the fall meeting of the American Geophysical Union in San Francisco.
The gradual buildup of acidity in the atmosphere over a century got a boost around 1950 with a sharp increase in nitrogen-oxygen compounds, referred to as NOx, mainly produced in high-temperature combustion such as occurs in coal-fired power plants and motor vehicle engines. NOx is easily converted to nitric acid in the atmosphere, further increasing the acidity.

NOx carries a chemical signature — the abundance of nitrogen-15, one of two nitrogen isotopes — which changes depending on the source. That means it is possible to distinguish NOx that came from a forest fire from NOx produced as a result of lightning, soil emissions, car exhaust and power plant emissions. The level of nitrogen-15 can be measured in nitrates that formed from NOx and were deposited in ice sheets such as those in Greenland.

Current evidence indicates NOx from coal-fired power plant and motor vehicle emissions likely carries more nitrogen-15 than NOx produced by natural sources, so nitrogen-15 levels in deposited nitrate could be expected to go up. However, those levels actually went down in the late 1800s, following the Industrial Revolution, Geng said. That’s because increasing sulfuric acid levels in the atmosphere triggered chemical and physical processes that allowed less nitrogen-15 to remain in vaporized nitrate(NO3, the CAS number is 14797-55-8 or 84145-82-4), which can be carried to remote places such as Greenland. The growing acidity in the atmosphere was occurring decades before acid rain was recognized as a threat, particularly in industrial areas of North America.

“We’ve seen a huge drop in sulfate concentrations since the late 1970s,” Geng said. “By 2005, concentrations had dropped to levels similar to the late 1800s.” Ice core data show nitrate levels have stabilized during that time, he said, because while emission levels from individual vehicles might have decreased substantially, the number of vehicles has increased significantly.

Keeping ship hulls free of marine organisms

Special underwater coatings prevent shells and other organisms from growing on the hull of ships—but biocide paints are ecologically harmful. Together with the industry, researchers have developed more environmentally-friendly alternatives.

Every year, this so-called biofouling causes economic losses of billions of Dollar. Biological growth on the underwater surface promotes corrosion. The deposits increase the roughness of the hull below the waterline which has a braking effect as the ship travels. Depending on the roughness of the basified bio layer, the consumption of fuel can increase by up to 40 percent. In the case of a large container ship this can result in additional annual costs of several millions.

A good news is that researchers have developed a more ecologically-friendly alternative. “The electrochemically active coating system produces regularly changing pH values on the surface of the hull. This effectively prevents colonization without having to use any biocides”, explains Professor Manfred Füting of the IWM in Halle who is coordinating the project.

Large area electrodes were painted on an isolating primer coating. The electrochemical active layer based on a sol-gel paint of NTC (nano tech coating gmbH), which was modified by electrically conductive particles. A current density of lower than 0,2 mAcm-2 generates enough pH stress near the surface of the hull to prevent the growing on of any barnacles, shells and algae The electric current is supplied by a photovoltaic module or by the land based power grid.

All the countermeasures used to date have considerable drawbacks: Cleaning the hull by sandblasting in a dry dock removes also the painted coating and can only be used every three to five years. There are effective hull coatings preventing the growing of adhering bio layers, but in most cases by ecotoxic biocides. Both copper ions and synthetic biocides accumulate in the coastal water and in the sediments. For this reason the particularly toxic tributyltin (TBT) is banned since 2008 and the currently preferred and still permitted copper oxide containing coatings are to be replaced by non-toxic alternatives in the foreseeable future.

Tests with the first prototypes at the Barth shipyard were promising: differently coated and electrochemically active and passive large areas are currently tested to prove their long-term stability against hydrodynamic stress and efficiency to prevent adherence and growth of bio layers. To achieve the real applicability of an economically competitive and ecofriendly antifouling system follow-up projects are planned: “They will mainly involve improving the technical applicability and optimization of our electrochemical antifouling system, which then could be applied on ship hulls for at least 3 to 5 years”, states Futing.

Antiseptic Products In Healthcare

Did you wash your hands with soap before sitting down for dinner?You may forget it and can’t wait to eat foods. But did you know that washing hands is so important, it actually saves lives?

Ignaz Semmelweiss  – The saviour of mothers
Ignaz Semmelweiss was a doctor at the Vienna General Hospital from 1846 to 1865. He was greatly worried that too many women died during childbirth. After careful observations, he discovered that doctors who handled different patients accidentally caused infections in women who came to deliver babies. He started the practice of making all doctors and nurses wash their hands in chlorinated lime (now called calcium hypochlorite). Because of this, the rate of deaths declined sharply.

Semmelweiss developed a theory that there were tiny ‘particles’ that could be transmitted from body to body and caused diseases. However, no one believed him. Because of this, his practice was not adopted outside his own hospital.

Ignaz Semmelweiss first started the practice of making all doctors and nurses wash their hands before and after surgery.

Joseph Lister – the founder of antiseptic surgery
A doctor at the Glasgow Royal Infirmary called Joseph Lister  had similar thoughts to what Semmelweiss had. He wondered whether germs could be killed by chemical solutions. After a few experiments, he discovered that carbolic acid (now called phenol) was effective. He used it to clean surgical tables and instruments before and after surgery. Due to this, the survival of patients was greatly increased. Soon, carbolic soap was mandatory in all hospitals.

So why did Lister succeed while Semmelweiss did not?

The germ theory and modern antiseptics
Semmelweiss failed because he could not prove his theory. That proof came only in 1864, when Louis Pasteur demonstrated that microscopic bacteria caused diseases. This is now called the ‘germ theory of disease’. Pasteur’s published his discovery in a famous science journal that was read all over the world. When Joseph Lister came across this article, he could immediately explain why his carbolic soap was saving lives – it was killing the germs that cause disease.

Carbolic acid is no longer used as an antiseptic, as it is highly poisonous. Alcohol and iodine tincture (also known as Choleratoxin) are now preferred as they are safe. Boric acid is used as a dry antiseptic for fungal infections, and triclosan in toothpastes.

Strictly speaking, an antiseptic is a substance applied externally on human and animal bodies only. Anything used to sterilize clothes, floors, walls, surgical instruments, swimming pools etc is known as a disinfectant. Common disinfectants include chlorine, iodoform, hydrogen peroxide, and phenol. Chloroxylenol is used as both, going by the trade name of Dettol.

Harmful greenhouse gas can be used for making pharmaceuticals

A team of chemists at USC has developed a way to transform a hitherto useless ozone-destroying greenhouse gas that is the byproduct of Teflon manufacture and transform it into reagents for producing pharmaceuticals.

The team will publish their discovery in a paper entitled “Taming of Fluoroform (CF3H): Direct Nucleophilic Trifluoromethylation of Si, B, S and C Centers,” in the Dec. 7 issue of Science.

Because of the popularity of Teflon, which is used on everything from cooking pans to armor-piercing bullets, there’s no shortage of its waste byproduct, fluoroform. Major chemical companies such as DuPont, Arkema and others have huge tanks of it, unable to simply release it because of the potential damage to the environment. Fluoroform has an estimated global warming potential 11,700 times higher than carbon dioxide.

But one man’s trash is another man’s treasure, and G.K. Surya Prakash—who has spent decades working with fluorine reagents—saw the tanks of fluoroform as an untapped opportunity.

Prakash, a professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences and director of the USC Loker Hydrocarbon Research Institute, describes fluorine as “the kingpin of drug discovery.” About 20 to 25 percent of drugs on the market today contain at least one fluorine atom.

Fluorine can be found in all different kinds of drugs, everything from 5-Fluorouracil (a widely used cancer treatment discovered by Charles Heidelberger at USC in the ’70s) to Prozac to Celebrex.

“It’s a small atom with a big ego,” he said, referring to the fact that while fluorine is about the same size as a tiny hydrogen atom—so similar that living cells cannot tell the two elements apart—it is also extremely electronegative (that is, it has a strong attraction for electrons) making carbon-fluorine chemical bond quite strong, which improves the bioavailability of drugs made with fluorine.

The discovery was the product of many years of trial-and-error tests, hard work that the postdocs performed under Prakash’s direction. Eventually, the team pinned down the precise conditions needed to coax the harmful fluoroform (CF3H) into useful reagents, including the silicon-based Ruppert-Prakash Reagent for efficient CF3 transfer. Fluoroform with elemental sulfur was also converted to trifluoromethanesulfonic acid, a widely used superacid one-hundred times stronger than sulfuric acid.

“In real estate, everything is ‘location, location, location.’ In chemistry, it is ‘conditions, conditions, conditions,’” Prakash said.

Plastics used in medical devices break down

Scientists have discovered a previously unrecognized way that degradation can occur in silicone-urethane plastics that are often considered for use in medical devices. Their study, published in ACS’ journal Macromolecules, could have implications for device manufacturers considering use of these plastics in the design of some implantable devices, including cardiac defibrillation leads.

Kimberly Chaffin, Marc Hillmyer, Frank Bates and colleagues explain that some implanted biomedical devices, such as pacemakers and defibrillators, have parts made of a plastic consisting of polyurethane and silicone. While these materials have been extensively studied for failure due to interaction with oxygen, no published study has looked at interaction with water as a potential failure mechanism in this class of materials. In a cardiac lead application, these materials may be used as a coating on the electrical wires or “leads” that carry electric current from the battery in the device to the heart. Surgeons implant pacemakers in 600,000 people worldwide and defibrillators in 100,000 people in the United States each year. Since these implants must function reliably for years, the scientists wanted to determine whether the plastic material was suitable for long-term implants.

Segmented polyurethane multiblock polymers containing polydimethylsiloxane(CAS number is 541-02-6) and polyether soft segments form tough and easily processed thermoplastic elastomers. Their laboratory tests, including accelerated aging of the materials under conditions that simulated the inside of the human body, found indications that the material begins to break down within 3-6 years. “By making the conclusions of this novel, scientific research public in a respected peer-reviewed journal, device manufacturers may now consider these important findings in their device designs,” says Chaffin, distinguished scientist and lead author of the manuscript.

Improved performance for solar cells

Photovoltaics is still an expensive technology. Dye-based solar cells may represent a more cost-effective alternative to traditional solar cells. In these cells, a dye is used in place of a semiconductor to trap the light. Tandem cells consisting of both a conventional n-type and an “inverse” p-type dye-sensitized solar cell seem to be especially promising.

In the journal Angewandte Chemie, a team of Australian and German scientists has now reported a significant increase in the degree of efficiency of p-type dye-sensitized solar cells through use of an electrolyte based on a cobalt complex.

Conventional n-type dye-sensitized solar cells use a photoanode, a positive electrode coated with an n-type semiconductor, such as titanium dioxide, and a dye. When light strikes the electrode, the dye molecules become excited and release electrons—negative charges, hence the n in n-type—and “inject” them into the n-type semiconductor. The redox mediator, a component of the electrolyte that can move freely between the electrodes, regenerates the dye by resupplying it with electrons from the counter electrode. In a p-type cell, the process is reversed: a special dye and a p-type semiconductor are located on a photocathode. The light-activated dye “sucks” electrons out of the valence band of a p-type semiconductor such as nickel oxide. This effectively transfers “electron holes”—positive charges, hence the p in p-type—from the dye. The redox mediator takes the electrons from the dye and hands them over to the counter electrode.

A very promising approach for increasing the performance of photovoltaic cells is to combine both an n-type and a p-type dye-sensitized solar cell to make a tandem cell. However, despite some progress, the performance of the p-type cells still significantly lags behind that of their n-type counterparts. An international team of researchers from Monash University and the Commonwealth Scientific and Industrial Research Organization (Australia), as well as the University of Ulm (Germany), have now achieved a considerable improvement in the efficiency of p-type cells by choosing a different redox mediator.

Researchers working with Udo Bach and Leone Spiccia replaced the previous, commonly used iodide and triiodide system with a well-known cobalt complex, tris(ethylenediamine)cobalt(III) , in which the cobalt can switch between the +2 and +3 oxidation states. The advantage of this system is that the redox potential is significantly lower. As a result, the open-circuit voltage, a critical parameter for solar cells, is doubled and there is still a high enough driving force to ensure rapid and efficient regeneration of the spent dye. These devices achieve an energy-conversion efficiency of 1.3 %, while previous systems attained a maximum of only 0.41 %. The p-type dye-sensitized solar cell with the cobalt-based redox mediator even gave promising performance data under diffuse sunlight experienced on cloudy days.

Garbage bug may help lower the cost of biofuel

One reason that biofuels are expensive to make is that the organisms used to ferment the biomass cannot make effective use of hemicellulose, the next most abundant cell wall component after cellulose. They convert only the glucose in the cellulose, thus using less than half of the available plant material.

“Here at the EBI and other places in the biofuel world, people are trying to engineer microbes that can use both,” said University of Illinois microbiologist Isaac Cann. “Most of the time what they do is they take genes from different locations and try and stitch all of them together to create a pathway that will allow that microbe to use the other sugar.”

Cann and Rod Mackie, also a U of I microbiologist, have been doing research at the Energy Biosciences Institute on an organism that they think could be used to solve this problem.

Specifically, the bacterium contains all of the proteins and enzymes needed to break down xylan, which is the most common hemicellulose, and then to transport the fragments into the cell and metabolize them. All of the genes are located in a single cluster on the microbe’s genome.

“So instead of taking a piece from here and from there and stitching them together, we can just take this part of the gene,” Cann explained. “You can cut this and put it into another microbe.”

On the surface of the cell, there is an enzyme that cuts the xylan into small pieces and a protein that binds to the pieces and brings them inside the cell. Enzymes within the cell metabolize the sugar.

The reason that this microbe, unlike most others used to make biofuels, is able to degrade xylan is that it has evolved an enzyme that allows it to remove the side chains, or decorations, that are part of xylan’s structure. They hinder the degradation process by preventing complete accessibility of the enzymes to the sugar chain.

Having the enzymes next to each other on the genome is convenient for scientists who are working on engineering microbes that can degrade both cellulose and hemicellulose. The cluster could be designed as a cassette and put into a microbe that normally degrades only cellulose.

Moreover, being next to each other allows them to work efficiently. “You have a set of enzymes that have co-evolved,” Cann explained. “If they have co-evolved over millions of years, it means they have been fine-tuned to work together.”

Put a lab on a chip

A team of URI engineers and students has developed (and are patenting) an advanced blood-testing technology that incorporates a Smartphone application, hand-held biosensor and credit card-sized cartridge to provide rapid, accurate biological analysis and wireless communication of blood test results.

“Today when you go to the lab to have a blood test, they take vials of liquid from you and you have to wait sometimes days to get the results,” said Mohammad Faghri, URI professor of mechanical engineering and the lead researcher on the project. “With our system, and just a drop of blood, you can have your blood tested when you walk into the doctor’s office and the results will be ready before you leave. Or you can do it at home and have the results sent to your doctor in real time.”

It’s the next step in an ongoing lab-on-a-chip project begun in 2005 by URI, in partnership with the Technical University of Braunschweig in Germany that has generated enthusiasm among many sectors of the health care industry. “This area of research has tremendous economic development potential for spin-off companies, patents, and workforce training,” Faghri said.

The technology has evolved since its conception in the form of several undergraduate, master’s, and doctoral projects, to a shoebox-size device for commercial application last year, to the current hand-held device with several additional capabilities.

“The Smartphone app turns the system on. Users place a drop of blood from a finger prick on a disposable plastic polymer(such as styrene, the CAS number is 91261-65-3) cartridge and insert it into the hand-held biosensor. The blood travels through the cartridge in tiny channels to a detection site where it reacts with preloaded reagents that allow the sensor to detect certain biomarkers of disease. And then it sends the results securely back to your phone or to your doctor, all in about 20 minutes,” Faghri said.

URI is known for our interdisciplinary programs, and the lab-on-a-chip project is one of them. It brings students and faculty from several engineering disciplines, chemistry, physics, molecular biology, and even entomology. Funded by the National Science Foundation and Rhode Island Science & Technology Advisory Council, URI’s lab-on-a-chip research and technology could revolutionize pharmaceuticals, early detection of infections, and other health-related fields. That’s just the kind of stuff we like to do here.

The substances behind the aroma in the king of fruits

The latest effort to decipher the unique aroma signature of the durian—revered as the “king of fruits” in southeast Asia but reviled elsewhere as the world’s foulest smelling food—has uncovered several new substances that contribute to the fragrance. The research appears in ACS’ Journal of Agricultural and Food Chemistry.

Martin Steinhaus and colleagues explain that durian, available in Asian food shops in the United States and elsewhere, has a creamy yellowish flesh that can be eaten fresh or used in cakes, ice cream and other foods. Some people relish the durian’s smell. Others, however, regard it as nauseating, like rotten onions. Past research identified almost 200 volatile substances in durian. Lacking, however, was information on which of those make a contribution to the characteristic durian smell. The authors set out to identify the big chemical players in the durian’s odor signature.

An aroma extract dilution analysis applied on the volatile fraction isolated from Thai durian by solvent extraction and solvent-assisted flavor evaporation resulted in 44 odor-active compounds in the flavor dilution (FD) factor range of 1–16384, 41 of which could be identified and 24 that had not been reported in durian before. High FD factors were found for ethyl (2S)-2-methylbutanoate (fruity; FD 16384), ethyl cinnamate (honey; FD 4096), and 1-(ethylsulfanyl)ethanethiol (roasted onion; FD 1024), followed by 1-(ethyldisulfanyl)-1-(ethylsulfanyl)ethane (sulfury, onion), 2(5)-ethyl-4-hydroxy-5(2)-methylfuran-3(2H)-one (caramel), 3-hydroxy-4,5-dimethylfuran-2(5H)-one (soup seasoning), ethyl 2-methylpropanoate (fruity, also known as ethyl isobutyrate), ethyl butanoate (fruity), 3-methylbut-2-ene-1-thiol (skunky), ethane-1,1-dithiol (sulfury, durian), 1-(methylsulfanyl)ethanethiol (roasted onion), 1-(ethylsulfanyl)propane-1-thiol (roasted onion), and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (caramel). Among the highly volatile compounds screened by static headspace gas chromatography–olfactometry, hydrogen sulfide (rotten egg), acetaldehyde (fresh, fruity), methanethiol (rotten, cabbage), ethanethiol (rotten, onion), and propane-1-thiol (rotten, durian) were found as additional potent odor-active compounds.

In doing so, they pinpointed 41 highly odor-active compounds, 24 of which scientists had not identified in durian before. Among the most prominent were substances associated with fruity, sweet, sulfurous and oniony smells. The oniony smelling odorants belonged to a compound class that had rarely been found in food before. Four of the newly discovered chemical compounds were previously unknown to science.

New Type Of Plastics

Things made of plastic, from credit cards to spoons to bags, have become so common in our lives that we can hardly think of life without them. Yet all plastics are made from petroleum, which will run out in a few decades. What do we do next?

How plastics are made
All plastics are polymers, that is they are made of a molecule which is itself made of hundreds of small molecules. These units are called monomers. Polyethylene (used in plastic bags) is made from a monomer unit called ethylene. Similarly styrofoam (used in disposable cups and plates) is made from a unit called styrene. PVC, which is used to make things like buckets and even plastic doors, is made from units of vinyl chloride linked to each other by chemical bonds. All these units ultimately come from petroleum. But the reserves of petroleum are quite rare, and will run out in our lifetime.

Plastic from potatoes
Potatoes contain a lot of starch (cellulose), which can be used to make a plastic-like material quite easily and cheaply. This plastic is not very strong or long-lasting. It is also very easily broken down by bacteria (see an article about eco-friendly plastic here). But that makes it the ideal material for making disposable spoons, cups, plates etc. In fact many companies have already begun to do so, and they have given it a nice name too – Spudware!

Plastic from chicken feathers and soybeans
The circuit board you see on electronic devices is made of a light but durable plastic, on which tiny electronic circuits are soldered on. As computers, mobile phones and other electronic gadgets spread through the world, we’ll need millions of these feather-bean boards!

A team from Cornell University found another way to make plastic. They used orange peels, and another material that is becoming increasingly common in our atmosphere – carbon dioxide. Orange peels contain a chemical called limonene (the same thing that gives the orange-y smell). The team found that you can convert it to limonene carbonate, which could then be polymerised into a useful plastic called poly-limonene carbonate (PLC). This is in fact a de-polluting plastic, because to make it you need to remove CO2 from the air, rather than add to it.

We hope that you’ll be inspired to make something equally clever from materials lying around the house too!

Researchers develop method for creating artificial fingerprints

A trio of researchers at the National Institute of Standards and Technology (NIST) in Maryland has found a way to accurately recreate human fingerprints. The reason for doing so, the team writes in their paper published in the journal Analytical Methods, is to provide a means for testing fingerprints for other chemicals as part of forensics research efforts.

Scientists know that when people work with explosives or illegal substances such as drugs, tiny amounts of those substances are captured in the oils produced in the fingers and are subsequently left behind in fingerprints when those people touch something else. Forensic research has focused on ways to recreate the process in an artificial way to better understand what properties are involved so as to better understand what occurred before, during or after a crime has been committed.

Researchers at NIST are hoping to discover new analysis techniques that will reveal more information about a person who has left fingerprints at a crime scene. By recreating the process in a controlled way, it becomes possible to vary environmental conditions to see what impact they might have on prints that are left behind.

Previous attempts to create artificial fingerprints have revolved around inkjet printing techniques, but have failed due to the oily nature of the materials involved, principally, sebum, the oil that is actually found in human fingerprints. The new method developed by the team at NIST takes a different approach.

The team created a solution by dissolving sebum in heptane to cause it to liquefy, then added particles of an explosive material followed by polyisobutylene to force the particles to remain suspended in the solution. To apply the solution they built a device that has a pneumatically controlled piston inside of a tube with a ball on the end (similar to an ink pen) that allows a controllable amount of the solution to pass through when pressed against a surface. Upon application, the solvents evaporate leaving just the sebum with the suspended particles still in it. In refining the piston-ball configuration, the team has found that they were able to apply the material onto surfaces in pattern shapes that resemble human fingerprints.

Light and air: Sunlight-driven CO2 fixation

The increased use of renewable energy sources, particularly sunlight, is highly desirable, as is industrial production that is as CO2-neutral as possible. Both of these wishes could be fulfilled if CO2 could be used as the raw material in a system driven by solar energy. Japanese researchers have now introduced an approach to this type of process in the journal Angewandte Chemie. Their method is based on a principle similar to natural photosynthesis.

The use of carbon dioxide as a source of carbon may be an attractive option for reducing the consumption of fossil feedstocks and improving the CO2 footprint of chemical products. The biggest obstacle in our way is the high stability of the CO2 molecule. One of the possibilities for jumping this hurdle is to use very high-energy molecules to react with CO2. The photosynthetic process in green plants provides an example of how this could work. This process takes place in two steps: the light reactions and the dark reactions. In the light reactions, the photosynthetic system captures photons and stores their energy in the form of energetic chemical compounds. These are subsequently used to drive the dark reactions that use CO2 as a carbon source to synthesize complex sugar molecules.

Researchers working with Masahiro Murakami at Kyoto University used the same principle to design their process. In this case, the first step is also a reaction driven by light. The action of UV light can convert the starting material, an α-methylamino ketone, to a very energetic molecule. This also works with sunlight, as the researchers found out. An intramolecular rearrangement with ring closure results in a molecule containing a ring made of three carbon atoms and one nitrogen atom. This type of ring is under a great deal of strain and is correspondingly reactive. This “light reaction” was coupled to a “dark reaction”: In the subsequent light-independent step, the highly energetic compound captures CO2 in the presence of a base. This forms a cyclic amino-substituted carbonic acid diester (such as Carboni cacid allyl ethyl ester and the CAS number is 108-32-7that could be useful as an intermediate for chemical syntheses.

The striking thing about this reaction scheme is that the technique is simple. Diffuse sunlight on cloudy days is enough to drive the process. The second step can be carried out in the same reaction vessel through simple addition of the base and heating to 60 °C. The yield is 83 %. In addition, the process is very adaptable because a wide variety of α-methylamino ketones can be used as starting materials.

New injectable gels toughen up after entering the body

Gels that can be injected into the body, carrying drugs or cells that regenerate damaged tissue, hold promise for treating many types of disease, including cancer. However, these injectable gels don’t always maintain their solid structure once inside the body.

MIT chemical engineer Bradley Olsen and his his students have now designed an injectable gel that responds to the body’s high temperature by forming a reinforcing network that makes the gel much more durable, allowing it to function over a longer period of time.

However, a drawback of these materials is that after they are injected into the body, they are still vulnerable to mechanical stresses. If such stresses make them undergo the transition to a liquid-like state again, they can fall apart. “Shear thinning is inherently not durable,” Olsen says. “How do you undergo a transition from not durable, which is required to be injected, to very durable, which is required for a long, useful implant life?”

The MIT researchers designed their hydrogel to include a second reinforcing network, which takes shape when polymers attached to the ends of each protein bind together. At lower temperatures, these polymers are soluble in water, so they float freely in the gel. However, when heated to body temperature, they become insoluble and separate out of the watery solution. This allows them to join together and form a sturdy grid within the gel, making it much more durable.

The MIT team answered that question by creating a reinforcing network within their gels that is activated only when the gel is heated to body temperature (37 degrees Celsius). Shear thinning gels can be made with many different materials (including polymers such as polyethylene glycol, or PEG), but Olsen’s lab is focusing on protein hydrogels, which are appealing because they can be designed relatively easily to promote biological functions such as cellular adhesion and cell migration.

The researchers found that gels with this reinforcing network were much slower to degrade when exposed to mechanical stress and were significantly stiffer.

Another advantage of these gels is that they can be tuned to degrade over time, which would be useful for long-term drug release. The researchers are now working on ways to control this feature, as well as incorporating different types of biological functions into the gels.

Ingredient in diarrhea medicine leads to new farm fertilizer

The search for a sustainable slow-release fertilizer—a key to sustaining global food production at a time of burgeoning population growth—has led scientists to an ingredient used in some diarrhea medicines. They describe use of the substance, attapulgite, as a “carrier” for plant nutrients in a report in ACS’ journal Industrial & Engineering Chemistry Research.

This study was carried out to develop a novel slow-release fertilizer, which is based on natural attapulgite (APT) clay as a matrix, guar gum (GG) as an inner coating, and guar gum-g-poly(itaconic acid-co-acrylamide)/humic acid (GG-g-P(IA-co-AM)/HA) superabsorbent polymer as an outer coating. The coated compound fertilizer granules with diameter in the range of 2–3 mm possess low moisture content and high mechanical hardness.

Boli Ni and colleagues explain that about half of the 150 million tons of fertilizer used worldwide every year goes to waste. That’s because most fertilizers release nutrients too fast for the crops to use. The rest can run off farm fields and create water pollution problems. Existing slow-release fertilizers have drawbacks. So Ni’s team turned to the environmentally friendly substance attapulgite, an inexpensive, nutrient-rich clay used for decades to treat diarrhea and for other applications. It once was an ingredient in the Kaopectate marketed in the United States. They also included guar gum, used in cosmetics and to thicken foods, and humic acid (its CAS number is 1415-93-6) from decayed plant material.

The report describes development and successful tests of a new fertilizer composed of those three ingredients. The experimental data and analysis in this study indicated that the product prepared by a simple route can effectively reduce nutrient loss in runoff or leaching, improve soil moisture content, and regulate soil acidity and alkalinity level.
The slow-release pellets were easy to prepare, reduced nutrient loss via runoff and
leaching, improved soil moisture content and regulated soil acidity and alkalinity. “All of the results indicate that it may be expected to have wide applications for sustainable development of modern agriculture,” the scientists say.

Understanding Antibiotic Resistance

Scientists at the University of Bristol, together with collaborators at the University of Aveiro, Portugal, have solved the structure of an enzyme that breaks down carbapenems, antibiotics ‘of last resort’ which, until recently, were kept in reserve for serious infections that failed to respond to other treatments.

Increasingly, bacteria such as E. coli are resisting the action of carbapenems by producing enzymes (carbapenemases) that break a specific chemical bond in the antibiotic, destroying its antimicrobial activity.

Carbapenemases are members of the group of enzymes called beta-lactamases that break down penicillins and related antibiotics, but it has not been clear why carbapenemases can destroy carbapenems while other beta-lactamases cannot.

Using molecular dynamics simulations, Professor Adrian Mulholland in the School of Chemistry and Dr Jim Spencer in the School of Cellular and Molecular Medicine, showed how a particular type of carbapenemase enzyme reorients bound antibiotic to promote its breakdown and render it ineffective.

“The recent appearance and spread of bacteria that resist carbapenems is a serious and growing problem: potentially, we could be left with no effective antibiotic treatments for these infections. The emergence of bacteria that resist carbapenems is therefore very worrying.”

In a study published in the Journal of the American Chemical Society (JACS), the scientists combined laboratory experiments with computer simulations to investigate how one particular type of carbapenemase recognises and breaks down antibiotics. In beta-lactamase (the CAS number is 9073-60-3 or 9001-74-5) that cannot break down carbapenems, this rearrangement cannot happen, and so the enzyme cannot break down the antibiotic. Knowing this should help in designing new drugs that can resist being broken down.

Dr Spencer said: “Combining laboratory and computational techniques in this way gave us a full picture of the origins of antibiotic resistance. Our crystallographic results provided structures which were the essential starting point for the simulations and the simulations were key to understanding the dynamic behaviour of the enzyme-bound drug.

“Identifying the molecular interactions that make an enzyme able to break down the drug, as we have done here, is an important first step towards modifying the drug to overcome bacterial antibiotic resistance.”

Chemist develops spray to detect poison oak’s toxic oil

The last time Rebecca Braslau got a bad case of poison oak, she found herself pondering the chemical structure of urushiol, the toxic oil in poison oak and its relatives, poison ivy and poison sumac (all species of Toxicodendron).

“I thought: I’m a chemist. I should be able to do something about this,” said Braslau, a professor of chemistry and biochemistry at the University of California-Santa Cruz. Now her lab has developed a spray that can be used to detect urushiol on clothes and equipment, and potentially on skin, allowing people to wash off the oil before it causes an itchy, blistering skin rash.

Exposure to tiny amounts of urushiol is enough to cause this allergic reaction in susceptible people, and about 70 percent of U.S. adults are clinically allergic to urushiol or would become allergic if exposed enough times. Although Braslau said she doesn’t think there are toxicity concerns with any of the components of the spray, toxicology tests would be required before it could be approved for use on the skin.

“Of course, it would be great if we could deactivate the oil, but just being able to see it is useful because then you can wash it off,” she said. “People can keep getting exposed from items with the oil on them. About 10 percent of firefighters have to take time off work due to poison oak, and some of that is from exposure to oil that gets on their equipment.”

Chemically, urushiol belongs to a class of compounds known as catechols, which have a characteristic ring structure. Urushiol has a long greasy tail or “sidechain” attached to the ring, and different mixtures of urushiols with slightly different sidechains are found in the various Toxicodendron species.

Braslau’s spray detects the catechol ring structure. It contains a mixture of compounds, including a “profluorescent” compound in which the fluorescence of a dye molecule is quenched, and reaction with urushiol allows the dye to light up.

The formula has been patented, but Braslau said more work is needed to make it into a marketable product. She is also interested in developing it into a technique to detect catecholamines, which include physiologically important molecules such as dopamine and epinephrine.

Braslau’s work on this project has not been funded by any major grants, aside from a small starter grant from her university. Her lab is continuing to do some work on it, mostly experimenting with different dyes. Developing it into a commercial product, however, will require an investor willing to fund additional research, she said.

A simpler path to a catalyst

Researchers at ETH Zurich developed a new synthesis procedure for a catalyst. This procedure may be used for the large-scale production of, for instance, plastics from renewable resources in an environmentally friendly and efficient manner.

It started with an idea of Ive Hermans, Assistant Professor at the Institute of Chemical and Bioengineering: The chemist and his co-workers were looking for a new synthesis procedure for an important catalyst for the chemical industry. To date, the synthesis of the catalyst occurs in a very complex and error-prone procedure. The ETH researchers discovered a far more convenient two-step procedure, which is more suitable for large-scale production.

The catalyst in question is a zeolite, a powdery, porous, particulate material. Like all catalysts also this substance can accelerate a certain reaction and/or steer it towards a desired product. Hermans and his co-workers wanted to develop a catalyst that facilitates oxidation reactions and can thus be used for the preparation of so-called lactones from ketones.

The use of a catalyst for such reactions has many advantages. “The preparation of lactones, for instance, is time-intensive and expensive, as acids are formed as side-products”, says Hermans. By using a tin containing zeolite as a catalyst instead, it becomes possible to use hydrogen peroxide as an oxidation reagent so that water is the only side-product. This method has not been implemented industrially so far, due to the time-consuming synthesis procedure of the special zeolites: the process requires 40 days. In addition, the procedure is difficult to control and can easily fail. Experiments have shown that the newly prepared zeolite contains more tin than conventionally prepared catalysts. Due to that, the catalyst is significantly more efficient.

In cooperation with an industrial partner, the ETH researchers want to optimize the preparation procedure for large-scale applications. In the future, the catalyst could be used for the industrial synthesis of starting materials required for important plastics. One example would be the preparation of polylactic acid from renewable resources. Polylactic acid is being used in plastic packing materials or foil. “The demand for plastics made from renewable resources will strongly increase as soon as crude oil – the basis of many plastics – will become more rare and expensive”, explains Hermans. “With our catalyst, it is possible to produce such products on a large scale in a much more environmentally friendly way. “

High-quality Products From Rubber Residues

Each year throughout the world, up to 22 million tons of rubber are processed and a large portion of it goes into the production of vehicle tires. Once the products reach the end of their useful life, they typically land in the incinerator. In the best case, the waste rubber is recycled into secondary products. Ground to powder, the rubber residues can be found, for example, in the floor coverings used at sports arenas and playgrounds, and in doormats.

But until now, the appropriate  techniques for producing high-quality materials from these recyclables did not exist. Researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen recently succeeded in optimizing the recycling of rubber waste materials. They have developed a material that can be processed into high-quality products, like wheel and splashguard covers, handles, knobs and steerable castors.

The new plastic compounds are called elastomer powder modified thermoplastics or EPMT for short. They are comprised of rubber residues crushed into elastomer powder that are blended with thermoplastics. EPMT can be easily  processed in injection molding and extrusion machines, and in turn, these products are themselves recyclable. The physical and mechanical material properties of the substance – like elasticity, breaking strain and hardness – can be individually modified, according to the customer’s wishes.

The crushing of rubber waste is more environmentally-friendly and resource-efficient than producing new rubber products – an important aspect in view of the rising costs of energy and raw materials. The researchers are capable of producing 100 to 350 kilograms of EPMT per hour. Spurred on by this success, Wack and both of his colleagues founded Ruhr Compounds GmbH. In addition to the production and the sale of EPMT materials, this Fraunhofer spin-off offers custom-made service packages

The widest array of industries will benefit from the expertise of these professionals: processors of thermoplastic elastomers can obtain EPMT and further process it into products. Industrial companies whose work involves elastomers – such as  the industrial and construction sectors, or car-makers and athletics – could recycle these products, make EPMT from them, incorporate them into their existing products and thereby close the materials cycle.

In the “Re-use a Shoe” project, sports gear maker Nike has been collecting used sneakers for a while now, recycled their soles and under the label “Nike Grind”, reprocessed them as filler material for sports arenas and running track surfaces. The EPMT compound of the Fraunhofer researchers enables Nike to place new products on the market.