Daily Archives: January 7, 2017

Glowing Crystals Can Detect, Cleanse Contaminated Drinking Water

Tiny, glowing crystals designed to detect and capture heavy-metal toxins such as lead and mercury could prove to be a powerful new tool in locating and cleaning up contaminated water sources.

Motivated by publicized cases in which high levels of heavy metals were found in drinking water in Flint, Mich., and Newark, N.J., a science team led by researchers at Rutgers University used intense X-rays at Lawrence Berkeley National Laboratory (Berkeley Lab) to probe the structure of the crystals they developed and learn how they bind to heavy metals.

Researchers have developed a specialized type of glowing metal organic framework, or LMOF (molecular structure at center), that is designed to detect and remove heavy-metal toxins from water. At upper left, mercury (Hg) is taken in by the LMOF. The graph at lower left shows how the LMOF’s fluorescence is turned off as it binds up the mercury. Its properties make this LMOF useful for both detecting and trapping heavy-metal toxins. Credit: Rutgers University

Researchers have developed a specialized type of glowing metal organic framework, or LMOF (molecular structure at center), that is designed to detect and remove heavy-metal toxins from water. At upper left, mercury (Hg) is taken in by the LMOF. The graph at lower left shows how the LMOF’s fluorescence is turned off as it binds up the mercury. Its properties make this LMOF useful for both detecting and trapping heavy-metal toxins. Credit: Rutgers University

The crystals function like miniature, reusable sensors and traps, and are known as luminescent metal-organic frameworks, or LMOFs.

Top performer for detecting and trapping heavy metals

One type of LMOF that the team tested was found to selectively take up more than 99 percent of mercury from a test mixture of heavy and light metals within 30 minutes, according to recent results published in Applied Materials and Interfaces. No other MOFs have performed as well in this dual role of detecting and capturing, or “adsorbing,” toxic heavy metals, the team reported.

Simon Teat, a Berkeley Lab staff scientist, studied individual LMOF crystals, each measuring about 100 microns (millionths of a meter), with X-rays at the lab’s Advanced Light Source (ALS). Using diffraction patterns produced as the X-ray light struck the LMOF samples, Teat applied software tools to map their three-dimensional structure with atomic resolution.

A research team used Berkeley Lab’s Advanced Light Source to determine the structure, shown here, of a luminescent metal-organic framework known as LMOF-261. The chemical components and large channels in the LMOF allow it to trap heavy metals. Credit: Rutgers University

A research team used Berkeley Lab’s Advanced Light Source to determine the structure, shown here, of a luminescent metal-organic framework known as LMOF-261. The chemical components and large channels in the LMOF allow it to trap heavy metals. Credit: Rutgers University

The ALS is one of just a few synchrotron X-ray light sources in the world that have dedicated experimental stations for chemical crystallography studies of crystallized chemical compounds such as MOFs.

It all starts with structure

What he found was a patterned, grid-like 3-D structure containing carbon, hydrogen, oxygen, nitrogen, and zinc atoms that framed large, open channels. These atomic-scale structural details are key to understanding how the LMOFs bind heavy metals, and can also aid in designing more highly specialized structures.

“With MOFs, you’re typically interested in using the holes for something,” Teat explained. In this case, the structure allows heavy metals to enter these open channels and chemically bind to the MOFs.

Their very open framework gives the MOFs an abundant surface area relative to their size, which allows them to take in a large amount of contaminants.

The LMOF structure was engineered to glow by incorporating a fluorescent chemical component, or ligand. “When the metal binds to the fluorescent ligand, the resulting framework fluoresces,” Teat said. The fluorescence of the LMOFs switches off when they interact with the heavy metals.

According to Jing Li, a chemistry professor at Rutgers University who led the research, the technology could be a money-saving solution. “Others had developed MOFs for either the detection of heavy metals or for their removal, but nobody before had really investigated one that does both,” Li added.

Intense X-rays produced at synchrotrons are the best way to map the 3-D structure of the MOFs, Li said, adding, “Knowing the crystal structures is one of the most important aspects of our research. You need those in order to perform subsequent characterizations and to understand the properties of these materials.”

Tests show MOFs are chemically selective, reusable

In their tests, researchers found that the LMOFs bind strongly to mercury and lead, but bind weakly to lighter metals such as magnesium and calcium that are also found in water supplies but do not pose the same hazards.

This selective trait, based on the molecular makeup of the LMOFs, is important, Li said. “We need to have a MOF that is selective and will only take the harmful species.”

The LMOFs can also be recycled. Researchers found that they could collect, clean, and then reuse the LMOFs for three cycles of toxic cleansing before their performance began to degrade.

What’s next?

The study notes that heavily industrialized areas, cities with antiquated water regulations, and agricultural communities can be particularly susceptible to groundwater contamination, which can lead to soil contamination if not addressed. This can cause the contaminants to be taken up by plants and animals in the surrounding environment, broadening the pathways of exposure.

Li said that further RD could explore lower-cost and more durable LMOFs that could last for more cycles, and researchers could also pursue the development of water filters by blending the LMOFs with polymers to create a solid film. “These filters could be used for capture on a larger scale,” she said.

“We would like to continue with this research,” Li said, adding that her team would like to test the system’s performance on actual contaminated water sources if funding becomes available. “These are promising results, but we have a long way to go.”

Her team also has used Berkeley Lab’s ALS to determine the crystal structures of MOFs for a wide variety of other applications, including high-explosives detection; toxin detection in foods; and new types of light-emitting components for LEDs, known as phosphors, that incorporate cheaper, more abundant materials.

The Advanced Light Source is a DOE Office of Science User Facility.

Researchers from the University of Texas at Dallas and Rider University also participated in this research. The work was supported by the DOE Office of Science.

Source: LBL

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Scientists Bring Silicon to Life through Directed Evolution

Up until now, forging silicon-carbon bonds in molecules has only been possible through chemical engineering, as they do not exist without human interference (at least as far as we know). The resulting compound, called organosilicon, can be found in pharmaceuticals, agricultural chemicals, semiconductors, adhesives, and computer and TV screens.

Directed evolution can strong-arm dynamic natural systems to start incorporating silicon into carbon-based molecules. Image credit: Th. Voekler via Wikimedia.org, CC BY-SA 3.0.

Now, however, researchers have discovered a way to produce the bond via natural means, essentially forcing nature to do our bidding. According to the authors of a new study, published in the November 24 issue of Science, this might help make organosilicon more environmentally-friendly and potentially less expensive.

Scientists and science fiction writers alike have long wondered whether life on Earth and possibly other planets could have evolved to be based on silicon instead of carbon. Given the similarity of their chemical composition, there doesn’t seem to be any logical contradiction in assuming that silicon-based life-forms exist somewhere in the Universe.

Both silicon and carbon have the capacity to form bonds to four atoms simultaneously, making them well-suited to producing the long chains of molecules that comprise life-as-we-know-it, such as proteins and DNA.

This is the first study to demonstrate just how easily and quickly natural systems can adapt to incorporating silicon into carbon-based molecules.

“No living organism is known to put silicon-carbon bonds together, even though silicon is so abundant, all around us, in rocks and all over the beach,” said Jennifer Kan, a postdoctoral scholar and the lead author on the study.

In order to achieve the desired result, researchers leaned on directed evolution, a method used for developing superior, artificial enzymes under lab conditions that was pioneered in the 1990s by Caltech professor Frances Arnold, who is also a co-author on the new study.

Directed evolution proceeds by selecting an enzyme that scientists want to enhance, which is then subjected to mutagenesis that brings about changes in its DNA coding. After picking the best one of the batch, the process is repeated until the enzyme performs as intended.

For the study, the research team picked a protein called cytochrome c. Although, normally, the protein is known to shuttle electrons to other proteins, the team also found it to act like an enzyme producing silicon-carbon bonds at low levels.

After only three rounds of directed mutations in the region of the protein’s DNA thought to be responsible for the activity, the researchers were able to create an enzyme that can selectively make silicon-carbon bonds 15 times more efficiently than the best catalysts currently available to science.

The new, iron-based, genetically encoded catalyst is non-toxic, cheaper and easier to modify than its rivals, operational at room temperature and in water, and, thanks to its selectivity, produces much fewer byproducts.

“The DNA-encoded catalytic machinery of the cell can rapidly learn to promote new chemical reactions when we provide new reagents and the appropriate incentive in the form of artificial selection. Nature could have done this herself if she cared to,” concludes Arnold.

Source: sciencedaily.com.

Drawing From Microalgae As A Sustainable Resource

A barrel of microalgae has a lot to offer – the chemical compounds to make biodiesel, pharmaceuticals, and infant formula, to name just a few things. But getting all those things from the same barrel is no easy trick.

tag

Creating a bio-based economy, however, depends on finding cost-effective ways to produce biofuels and other products from a sustainable feedstock. To that end, researchers in the lab of Julie Zimmerman, professor of chemical and environmental engineering, have developed a method that not only extracts different compounds from microalgae – a microscopic form of algae – but separates those compounds by type for different uses. The results of their work are published in ACS Sustainable Chemistry Engineering.

In the recent study, the researchers specifically targeted triacylglycerides (TAGs). One of the valuable compounds that can be found in microalgae, the molecular structure of TAGs looks very similar. What sets different types of TAGs apart from each other are their carbon chain lengths and whether those carbons are attached by single or double bonds.

One approach for extracting TAGs from algae involves the use of carbon dioxide (CO2). While this method can extract high volumes of TAGs, simultaneously separating TAGs by type has been a challenge. With conventional methods, they all come out together, like “a big soup.”

The Yale researchers, however, developed a method to separate and purify the TAGs from microalgae. With a process called fractionation, they can essentially “tune” the extraction and target specific TAGs by adjusting the temperature and pressures of the CO2.

“Right now all the technologies and approaches target one product – biofuel, for example,” said Thomas Kwan, a Ph.D. student and lead author of the study. “It’s cost-prohibitive because the biofuel alone doesn’t justify the costs.”

Kwan said the extraction and fractionation of TAGs is just one of the sustainable technologies the lab is developing for a broader bio-based economy. Other valuable compounds can be extracted from microalgae as well, such as beta-carotene and phospholipids. Kwan said the ability to extract and separate multiple products is crucial to make algae a sustainable source.

“Our approach is to say ‘There’s all kinds of stuff in this barrel of algae, so we should develop sustainable technologies to pull out every last drop of value from that algae,’” he said. “Look at oil – every last drop of it is used. Gasoline, kerosene, polymers, plastics, diesel – we get all kinds of stuff out of a barrel of crude oil.”

If you can do that with algae, he said, you can develop biorefineries that transform biomass into biofuels and other products.

Source: Yale University

Facial Recognition Market Expected to Reach US$ 2.67 Bn by 2022 Globally

According to a new market report published by Transparency Market Research “Facial Recognition Market – Global Industry Analysis, Size, Share, Growth, Trends and Forecast 2015 – 2022”, the global market for facial recognition is forecast to reach US$ 2,671.8 Mn by 2022. The market is driven by increased demand for surveillance systems by civil and government agencies.

This is majorly due to the rising number of crimes and terrorist activities across the globe that would elevate the demand for efficient facial recognition solutions/systems in the near future. In addition, acceptance of facial recognition in the entertainment industry coupled with extensive use of facial recognition in consumer electronics is expected to fuel the demand for facial recognition technology in future. The report provides in-depth analysis of the market by segmenting it on the basis of parameters such as technology type and end-use industry.

The global facial recognition market was valued at US$ 1,307.0 Bn in 2014 and is expected to grow at a CAGR of 9.5% from 2015 – 2022. The global facial recognition market comprises technology types as: 2D facial recognition, 3D facial recognition, and facial analytics. Of these, the market for 3D facial recognition technology segment, because of its high and better accuracy in terms of identifying facial features, is expected to record faster growth as compared to 2D facial recognition technology during the forecast period. In addition, growth of the market for facial analytics, an emerging technology used for examining facial images of people without disturbing their privacy, is further expected to record steady growth as compared to that for 2D facial recognition technology.

The demand for these facial recognition technologies is further influenced by increasing demand from various industries, namely, government and utilities, military, homeland security, retail, banking, financial services and insurance (BFSI), and others. Of these, government and utilities, which includes law enforcement and passport and visa programs, accounted for the largest share.

Further, with increased proliferation of retail outlets globally, facial recognition market is expected to experience significant growth in retail segment. This is supported by rising concerns of security and use of marketing strategies to analyze the customers based on their age, gender, and other facial attributes. It will thus, help in customer engagement at retail stores. Moreover, rising concerns of security have led companies to adopt tools such as CCTV recordings which are analyzed by facial recognition technique, alarm systems, and source-tagging.

Geographically, North America is expected to remain the largest regional market for facial recognition throughout the forecast period. This is mainly due to high expenditure on security systems in government as well as public sector. In addition to this, use of facial recognition technology by law enforcement agencies, military sector, and other public sector industries is expected to drive the market for facial recognition technology during the forecast period. Europe is also estimated to see increased adoption of facial recognition technology, with extensive demand for border control and identity validation applications.

Furthermore, the European Union (EU) is keen on developing better verification process for border control as maximizing security is of prime importance. Border control and identity validation has further gained importance due to rise in passport frauds and fundamental right for EU citizens, as guaranteed by the EU, which allows free movement of people across EU Schengen States. Moreover, active adoption of facial recognition technology across the Asia Pacific region due to rising population and need for surveillance systems in retail industry is expected to bolster demand in this region in the near future.

The global facial recognition market is dominated by players that develop facial recognition technology solutions. These players are continuously looking out for opportunities to strengthen their distribution network and to develop advanced solutions, so as to enhance their competitive position in the market. Globally, players such as NEC Corporation, Safran Group (Morpho S.A.), Cognitec System, and Cross Match Technologies are identified as the leading facial recognition algorithm developers and solution providers. Other prominent players in the market are 3M Cogent Inc., Aynoix Inc., FaceFirst LLC (Airborne Biometrics Group Inc.), Aware Inc., Animetrics, Inc., ZK Software, and Aurora Computer Services Ltd., among others.

Source: TMR

How the brain perceives rhythm

When it comes to perceiving music, the human brain is much more tuned in to certain types of rhythms than others, according to a new study from MIT.

A team of neuroscientists has found that people are biased toward hearing and producing rhythms composed of simple integer ratios — for example, a series of four beats separated by equal time intervals (forming a 1:1:1 ratio).

This holds true for musicians and nonmusicians living in the United States, as well as members of a Bolivian tribe who have little exposure to Western music. However, the researchers found that the Bolivians tended to prefer different ratios than Westerners, and that these ratios corresponded to simple integer ratios found in their music but not in Western music.

“Both of these cultures seem to prioritize rhythms that are formed by simple integer ratios. It’s just that they don’t prioritize all of them,” says Josh McDermott, the Frederick A. and Carole J. Middleton Assistant Professor of Neuroscience in the Department of Brain and Cognitive Sciences at MIT and the senior author of the study, which appeared in the journal Current Biology.

A team of neuroscientists has found that people are biased toward hearing and producing rhythms composed of simple integer ratios — for example, a series of four beats separated by equal time intervals. Image credit: MIT News

The paper’s lead author is Nori Jacoby, a former MIT postdoc who is now a Presidential Scholar in Society and Neuroscience at Columbia University.

Mental representations of rhythm

For this study, the MIT team devised a new way to reveal biases in the brain’s interpretation of sensory input. These biases, called “priors,” are thought to be based on our past experience of the world and to help resolve sensory stimuli that could be interpreted in multiple ways. For example, in a noisy room, priors on speech help you to extract a conversation of interest by biasing perception toward familiar speech sounds, words, and linguistic forms.

“You often rely on your prior knowledge of the states of the world that are more or less likely, to help relieve some of that ambiguity,” McDermott says. “When you get some piece of data and you have to make your best guess as to what’s actually out there in the world, you use the prior — the prior probability of different things in the world — to constrain your guess.”

To try to reveal priors for musical rhythm, the researchers first asked American college students to listen to a randomly generated series of four beats and then tap back the rhythm that they heard. The researchers recorded the taps and then played the tapped sequence back to the student, who tapped it out again. With each iteration, the new rhythm changed slightly, just as words morph as they are spoken from person to person in a game of “telephone.” Eventually, the tapped sequences became dominated by the listener’s internal biases. By running the procedure many times, Jacoby and McDermott were able to measure these biases for simple rhythms.

“It’s a way to probe the mental representation of what people unconsciously expect,” Jacoby says. “We wanted to find a way to ‘read their minds,’ but without requiring people to introspect or verbalize anything.”

After five iterations of the task, the rhythms that people produced were all approximated by ratios of simple integers — but not all such ratios were present. The rhythms corresponded to those most often heard in Western music, such as 1:1:2 and 2:3:3. However, the subjects did not produce ratios uncommon in Western music, such as 2:2:3, 3:2:2, and 2:3:2.

“The rhythms that have high probability in people’s heads seem to coincide with these simple integer rhythms that we know to be common in Western music,” McDermott says.

The researchers found the same results in musicians and nonmusicians, suggesting that the priors are formed by listening to music rather than making it.

Cultural comparisons

Next, the researchers performed the same study with members of the Tsimane tribe, who live in a remote part of Bolivia and have little exposure to Western music. In a study published earlier this year, McDermott and his colleagues found differences between Tsimane and Western preferences for chords. While Westerners dislike dissonant chords, such as the combination of C and F#, the Tsimane rated them just as likeable as “consonant” chords, which feature simple integer ratios between the acoustic frequencies of the two notes.

When musical rhythm was tested, the researchers found that, like Westerners, the Tsimane tended to produce rhythms consisting of simple integer ratios, but the ratios they generated were different than those preferred by Western subjects.

The rhythms favored by the Tsimane appear to be consistent with those that have been documented in the few records that exist of Tsimane music, McDermott says, a finding that offers evidence that priors are based on musical exposure.

“Using an iterated learning task, Western listeners could be compared to the Tsimane, as such giving insight into the process of cultural transmission and a possibly innate predisposition for small-integer-ratio rhythms,” says Henkjan Honing, a professor of music cognition at the University of Amsterdam, who was not part of the research team.

In future work, the researchers hope to use this technique to study other groups of people.

“What we plan on doing over the next year or two is to look at this in a number of different cultures and see how closely these priors mirror what we know about various cultures’ music,” Jacoby says.

Source: MIT, written by Anne Trafton