New method to sniff toxic gases from a distance

Scientists have developed a way to sniff out tiny amounts of toxic gases - a whiff of nerve gas, for example, or a hint of a chemical spill - from up to one kilometer away.

The new technology can discriminate one type of gas from another with greater specificity than most remote sensors - even in complex mixtures of similar chemicals - and under normal atmospheric pressure, something that wasn’t thought possible before.

The researchers say the technique could be used to test for radioactive byproducts from nuclear accidents or arms control treaty violations, for example, or for remote monitoring of smokestacks or factories for signs of air pollution or chemical weapons.

“You could imagine setting this up around the perimeter of an area where soldiers are living, as a kind of trip wire for nerve gas,” said lead author Henry Everitt, Army Scientist and Adjunct Professor, Duke University.

The technique uses a form of invisible light called terahertz radiation, or T-rays. Already used to detect tumors and screen airport passengers, T-rays fall between microwaves and infrared radiation on the electromagnetic spectrum. Zapping a gas molecule with a terahertz beam of just the right energy makes the molecule switch between alternate rotational states, producing a characteristic absorption spectrum “fingerprint,” like the lines of a bar code.

Terahertz sensors have been used for decades to identify trace gases in the dry, low-pressure conditions of interstellar space or in controlled conditions in the lab, where they are capable of unambiguous identification and ultra-sensitive, part-per-trillion detection.

But until now, efforts to use the same technique to detect trace gases under normal atmospheric conditions have failed because the pressure and water vapor in the air smears and weakens the spectral fingerprint.

In a study published in the journal Physical Review Applied, Everitt, Ohio State University physicist Frank De Lucia and colleagues have developed a way around this problem. Their approach works by blasting a cloud of gas with two beams at once. One is a steady terahertz beam, tuned to the specific rotational transition energy of the gas molecule they’re looking for. The second beam comes from a laser, operating in the infrared, which emits light in high-speed pulses.

At the US Army Aviation and Missile Research, Development, and Engineering Center near Huntsville, Alabama, the researchers have installed a one-of-a-kind infrared laser. Manufactured by a company called STI Optronics, it’s capable of firing dozens of pulses of infrared light a second, each of which is less than a billionth-of-a-second long. “It’s kind of like whacking a molecule with an infrared sledgehammer,” said Everitt.

Normal atmospheric pressure still blurs the chemical “bar code” produced by the blast of the Terahertz beam, but the ultra-short pulses of light from the more powerful infrared laser knock the molecule out of equilibrium, causing the smeared absorption lines to flicker.

“We just have to tune each beam to the wavelengths that match the type of molecule we’re looking for, and if we see a change, we know it has to be that gas and nothing else,” said Everitt.

The researchers directed the two beams onto samples of methyl fluoride, methyl chloride and methyl bromide gases in the lab to determine what combination of laser settings would be required to detect trace amounts of these gases under different weather conditions.

“Terahertz waves will only propagate so far before water vapor in the air absorbs them, which means the approach works a lot better on, say, a cold winter day than a hot summer day,” said Everitt.

The researchers say they are able to detect trace gases from up to one kilometer away. But even under ideal weather conditions, the technology isn’t ready to be deployed in the field just yet. For one, converting an eight-foot, one-tonne laser into something closer in size to a briefcase will take some time. Having demonstrated that the technique can work, their next step is to figure out how to tune the beams to detect additional gases.

Initially, they plan to focus on toxic industrial chemicals such as ammonia, carbon disulfide, nitric acid and sulfuric acid. Eventually, the researchers say their technique could also be useful for law enforcement in detecting toxic gases generated by meth labs, and other situations where detection at the gas’s source isn’t feasible.

“Point sensing at close range is always better than remote sensing if you can do it, but it’s not always possible. These methods let us collect chemical intelligence that tells us what’s going on before we get somewhere,” said Everitt.

Scientists make synthetic enzymes

In a major breakthrough, scientists have for the first time made synthetic enzymes - the vital ingredients needed for life - from artificial genetic material that does not exist outside the laboratory. The milestone could soon lead to new ways of developing drugs and medical treatments.

Medical Research Council (MRC) scientists said the enzymes were made from artificial genetic material. Their synthetic enzymes, which are made from molecules that do not occur anywhere in nature, are capable of triggering chemical reactions in the lab. The research gives new insights into the origins of life and could provide a starting point for an entirely new generation of drugs and diagnostics. The findings build on which saw them create synthetic molecules called ‘XNAs’ that can store and pass on genetic information, in a similar way to DNA.

Using their lab-made XNAs as building blocks, the team has now created 'XNAzymes', which power simple reactions, such as cutting up or stitching together small chunks of RNA, just like naturally occurring enzymes.

Dr Alex Taylor, the study’s first author said, “The creation of synthetic DNA, and now enzymes, from building blocks that don’t exist in nature also raises the possibility that, if there is life on other planets, it may have sprung up from an entirely different set of molecules, and it widens the possible number of planets that might be able to host life.”

DNA and RNA are the building blocks of life, storing all of our genetic information and passing it on to future generations.

Scientists who led the research at the MRC Laboratory of Molecular Biology, said, “All life on earth depends on a series of chemical reactions, from digesting food to making DNA in our cells. Many of these reactions are too sluggish to happen at ambient temperatures and pressures, and require enzymes to kick-start or ‘catalyse’ the process.”

Every one of our cells contains thousands of different enzymes, many of which are proteins. But some of the key fundamental reactions necessary for life are performed by RNA, a close chemical cousin of DNA. Life itself is thought to have begun with the evolution of a self-copying RNA enzyme.

“Until recently, it was thought that DNA and RNA were the only molecules that could store genetic information and, together with proteins, the only biomolecules able to form enzymes. Our work suggests that, in principle, there are a number of possible alternatives to nature’s molecules that will support the catalytic processes required for life. Life’s ‘choice’ of RNA and DNA may just be an accident of prehistoric chemistry,” explained Dr Taylor.

In 2012, the group showed that six alternative molecules, called XNAs, could also store genetic information and evolve through natural selection. They have now expanded on this principle to discover, for the first time, four different types of synthetic catalyst formed from these entirely unnatural building blocks.

The XNAzymes are capable of catalysing simple reactions like cutting and joining RNA strands in a test tube. One of the XNAzymes can even join XNA strands together, which represents one of the first steps to creating a living system.

Because their XNAzymes are much more stable than naturally occurring enzymes, the scientists believe they could be particularly useful in developing new therapies for a range of diseases, including cancers and viral infections, which exploit the body’s natural processes to take hold in the body.

“Our XNAs are chemically extremely robust and, because they do not occur in nature, they are not recognized by the body’s natural degrading enzymes. This might make them an attractive candidate for long-lasting treatments that can disrupt disease-related RNAs,” they added.

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Atmospheric carbon dioxide used for energy storage products

Chemists and engineers at Oregon State Universityhave discovered a fascinating new way to take some of the atmospheric carbon dioxide that’s causing the greenhouse effect and use it to make an advanced, high-value material for use in energy storage products.

This innovation in nanotechnology won’t soak up enough carbon to solve global warming, said researchers. However, it will provide an environmentally friendly, low-cost way to make nanoporous graphene for use in “supercapacitors” – devices that can store energy and release it rapidly. Such devices are used in everything from heavy industry to consumer electronics.

The findings were just published in Nano Energy by scientists from the OSU College of Science, OSU College of Engineering, Argonne National Laboratory, the University of South Florida and the National Energy Technology Laboratory in Albany, Ore. The work was supported by OSU.

In the chemical reaction that was developed, the end result is nanoporous graphene, a form of carbon that’s ordered in its atomic and crystalline structure. It has an enormous specific surface area of about 1,900 square meters per gram of material. Because of that, it has an electrical conductivity at least 10 times higher than the activated carbon now used to make commercial supercapacitors.

“There are other ways to fabricate nanoporous graphene, but this approach is faster, has little environmental impact and costs less. The product exhibits high surface area, great conductivity and, most importantly, it has a fairly high density that is comparable to the commercial activated carbons,” said Xiulei (David) Ji, Assistant Professor, OSU.

“And the carbon source is carbon dioxide, which is a sustainable resource, to say the least. This methodology uses abundant carbon dioxide while making energy storage products of significant value,” said Ji.

Because the materials involved are inexpensive and the fabrication is simple, this approach has the potential to be scaled up for production at commercial levels, said Ji.

The chemical reaction outlined in this study involved a mixture of magnesium and zinc metals, a combination discovered for the first time. These are heated to a high temperature in the presence of a flow of carbon dioxide to produce a controlled “metallothermic” reaction. The reaction converted the elements into their metal oxides and nanoporous graphene, a pure form of carbon that’s remarkably strong and can efficiently conduct heat and electricity. The metal oxides could later be recycled back into their metallic forms to make an industrial process more efficient.

By comparison, other methods to make nanoporous graphene often use corrosive and toxic chemicals, in systems that would be challenging to use at large commercial levels.

“Most commercial carbon supercapacitors now use activated carbon as electrodes, but their electrical conductivity is very low. We want fast energy storage and release that will deliver more power, and for that purpose the more conductive nanoporous graphene will work much better. This solves a major problem in creating more powerful supercapacitors,” said Ji.

A supercapacitor is a type of energy storage device, but it can be recharged much faster than a battery and has a great deal more power. They are mostly used in any type of device where rapid power storage and short, but powerful energy release is needed.

They are being used in consumer electronics, and have applications in heavy industry, with the ability to power anything from a crane to a forklift. A supercapacitor can capture energy that might otherwise be wasted, such as in braking operations. And their energy storage abilities may help “smooth out” the power flow from alternative energy systems, such as wind energy.

They can power a defibrillator, open the emergency slides on an aircraft and greatly improve the efficiency of hybrid electric automobiles. Nanoporous carbon materials can also adsorb gas pollutants, work as environmental filters, or be used in water treatment. The uses are expanding constantly and have been constrained mostly by their cost.

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New research shows link between global warming and carbon emission

Research has identified, for the first time, how global warming is related to the amount of carbon emitted. A team of researchers from the universities of Southampton, Bristol and Liverpool have derived the first theoretical equation to demonstrate that global warming is a direct result of the build-up of carbon emissions since the late 1800s when man-made carbon emissions began. The results are in accord with previous data from climate models.

The theoretical equation reveals the complex relationship between carbon dioxide levels and the ocean system. Burning fossil fuels increases atmospheric carbon dioxide levels leading to global warming and the greenhouse effect, which is partly offset by the oceans taking in both heat and carbon.

The results show every million-million tonne of carbon emitted will generate one degree Celsius of global warming. They also show that the build-up of carbon emitted over the last 200 years will then last for many centuries to millennia, even if carbon emissions are subsequently phased out.

The results also reveal that surface warming is related to the total amount of carbon emitted from fossil fuels, with little change over time as ocean carbon and changes in heat uptake almost cancel each other out.

“Our analysis highlights the nearly irreversible nature of carbon emissions for global warming. Once carbon has been emitted into the atmosphere the warming effect will last many centuries, even after much of the carbon has been absorbed by the ocean. We cannot wait until after significant anthropogenic warming has occurred to reduce carbon emissions and hope the climate goes back to normal by itself, it won’t,” said Dr Phil Goodwin, Ocean and Earth Science, University of Southampton.

“Given the complexity of the climate system, it was a surprise to find out how simple the relationship is between global warming and how much carbon we emit. The ocean turns out to be crucial by taking up both heat and carbon, which lead to nearly compensating effects in how surface warming depends on carbon emissions. These findings potentially address the most important finding from the Intergovernmental Panel on Climate Change (IPCC) report last year, which is how global warming increases with how much carbon we emit. In terms of wider policy implications, our theory reiterates a simple message: the more cumulative carbon emissions are allowed to increase, the more global surface warming will also increase. This policy implication reinforces the need to develop carbon capture techniques to limit the warming for the next generations,” said Ric Williams, Professor, Chair in Ocean Sciences, University of Liverpool.

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New method to determine surface properties at nanoscale

Engineering researchers at Texas Tech University have developed a method for characterizing the surface properties of materials at different temperatures at the nanoscale. Knowing properties of materials at different temperatures is important in engineering, said Gregory McKenna, Professor of chemical engineering and the John R Bradford Endowed, Chair in Engineering. For example, the rubber O-ring that failed during the 1986 space shuttle disaster serves at a tragic case study of what can go wrong when decision-makers don’t take this into account.

The problem, he said, is known properties of a material can radically change at the nanoscale – a tiny scale about 1/1000 of the diameter of a human hair at which scientists have begun building machines that do work. McKenna and graduate student Meiyu Zhai looked at several polymers and explosive materials to see how surface properties varied at the nanoscale and how the surface impacts the nanoscale properties.

Their first results on the “multi-curve method” appeared in the peer-reviewed journal, Journal of Polymer Science Part B: Polymer Physics and was highlighted in Advances in Engineering.

“The nanoscale is a funny range of sizes where materials have properties that are not what we expect, even at a step up at the microscale. We are developing methods to characterize surface properties and relate them to nanoscale behavior using a nanoindenter and other nano-mechanical measurement methods,” said McKenna.

In nanoindentation, researchers can investigate both the elastic properties (how materials spring back when pushed) or the viscous properties (how the material flows). The group has found several surprising results: for example, in other work, the team found extremely thin polycarbonate films become liquid-like at the nanoscale, while they are glassy at the macroscopic size scale. Nanoindentation can be used to relate surface properties to this observation. As machines get smaller and smaller, McKenna said, knowing this information can be invaluable to future engineers.

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New edible, antimicrobial film increases lifespan of soft cheese

Universitat Politecnica de Valencia (UPV) researchers have developed an edible, antimicrobial film that can increase the lifespan of soft cheese. They have used rosemary and oregano oils, and chitosan for producing the film.

Commercial soft cheese has a lifespan of about 21 days when treated with pimaricin and stored in cold storage. Excessive surface dehydration and micro-organism growth can cause deterioration of cheese. This may lead to formation of a slimy texture and odd odors and flavors. Pimaricin is a common antifungal agent that is used for preventing growth of fungus in cheese. Usually, a non-edible polyvinyl acetate plastic coating is also applied which aids in protecting the cheese.

When cheese matures, fungus can grow on its surface, and if the cheese surface has any fissures or faults, then the fungus can enter into these fissures. The newly developed coating can help decrease this growth of fungus on the surface of maturing cheese.

The innovative product developed by the researchers is a natural, edible coating that controls loss of weight and inhibits fungus growth. The researchers tested different oils and found that oregano oil was better than the other oils in preventing fungal growth. This provided the same results as when treated with pimaricin.

The researchers performed a sensorial analysis of the cheese with the edible coating. Over 100 panelists took part in the analysis. When compared with uncoated cheese, the cheese that was coated with essential oils such as oregano and rosemary, received better scores for odour and taste. This test also allowed the researchers to find out the optimum concentration of the essential oil that provided superior antifungal activity and good sensory acceptance.

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Most abundant mineral on earth named as, Bridgmanite

The most abundant mineral on earth that has remained nameless until now will be called Bridgmanite. After a team of American geologists were able to extract a sample large enough to analyze from a meteorite, Bridgmanite was named officially.

Until now, it was referred to as perovskite because according to rules set down by the International Mineralogical Association, a mineral cannot be given a formal name until a specimen has been found that can be examined first hand. The new name is in honour of Percy Bridgman, a pioneer in the use of high pressure experiments to better understand how many geological formations come about.

Bridgmanite makes up about 70 per cent of the earth’s lower mantle and 38 per cent of the total volume of earth. It is made up of high-density magnesium iron silicate.

The lower mantle which starts at 670km under the crust is difficult to reach for samples. The researchers looked at a meteorite that had fallen inside Australia in 1879 as a likely candidate for samples, and found what they were looking for.

Scientists had looked at likely candidate meteorites in the past, but the technique (electron diffraction) they used to look for a bit of perovskite wound up causing it to be destroyed. This time the team used a different, less destructive test - one that involved the use of a micro-focused X-ray beam in conjunction with electron microscopy. The researchers noted that the sample had more sodium and ferric acid than had been expected.

Their discovery is expected to aid future geological research and could offer clues about what goes on when celestial bodies collide, and potentially also about the formation of the universe.

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