Thursday, 18 August 2016

Sunshine, seaweed help to break down dye waste

Sunshine, seaweed help to break down dye waste:


The researchers developed a photocatalyst using titanium dioxide doped with red seaweed polymer carrageenan to degrade the dyes.
Scientists at the Central Salt & Marine Chemicals Research Institute (CSMCRI), Bhavanagar, Gujarat have been able to completely degrade three industrial dyes — methyl orange, methylene blue and reactive black-5 — in the presence of sunlight.
The researchers developed a photocatalyst using titanium dioxide doped with red seaweed polymer carrageenan to degrade the dyes. The results were published recently in the journal RSC Advances.
Despite stringent environmental regulations, a comprehensive method of treating industrial dye is not available. The methods available are expensive and do not completely break down the dye molecules to non-toxic constituents but merely concentrate the contaminants.
“Annually, more than 500 tonnes of non-degradable textile colour wastes are being disposed of in natural streams without adequate treatments,” the paper says.
Titanium dioxide has conventionally been used for photocatalytic degradation of industrial dyes, but it takes a long time to degrade dyes. So the researchers doped titanium dioxide nanoparticles with sulphur and carbon by treating it with carrageenan.
The nanocomposite was found to behave as an excellent photocatalyst that helped degrade industrial dyes quickly in a single-step process.
“The energy required to activate the catalyst is less when it is doped and this makes the dye degradation faster,” says Dr. Ramavatar Meena, the senior author of the paper from CSMCRI.
Solar concentrator used
Unlike a commercial titanium-dioxide-based catalyst that did not clear the dye solutions, the photocatalyst prepared in the lab was found to degrade the dyes when exposed to direct sunlight between noon and 2 pm during May-July.
“The Titanium-dioxide-doped photocatalyst degraded reactive black-5 and methylene blue in about one-and-half hours and 60 per cent of methyl orange in two hours,” says Dr. Meena. “Visible light is mainly responsible for degradation; ultraviolet radiation intensity was just 3 per cent.”
When a solar concentrator was used, the degradation process was hastened. “Reactive black-5 and methylene blue degraded within five minutes and methyl orange degraded completely in 20 minutes,” says Dr. Meena. There was no significant colour change in the case of control titanium dioxide sample that was not doped.
“When a solar concentrator is used the intensity of visible light is more and this plays an important role in the degradation process,” says Jai Prakash Chaudhary, the first author of the paper from CSMCRI.
The researchers are planning to conduct studies during winter to assess the photocatalyst’s ability to break down the dyes when bright sunlight is not available.
The nanocomposites are thermally stable and can be reused up to six times with the degradation efficiency remaining at over 97 per cent.
The nanocomposite photocatalyst can safely and completely treat harmful dyes in an eco-friendly and cost-effective manner, the study said.

Tuesday, 5 July 2016

New Nanoparticle Catalysts Improve Reactivity with Much Less Platinum

New Nanoparticle Catalysts Improve Reactivity with Much Less Platinum:

A sample of a core-shell nanoparticle made by the researchers is shown in images made using scanning transmission electron microscope (STEM) and energy-dispersive x-ray spectroscopy (EDX). Color images show where the different elements are located in the particle, with the precious metals platinum (Pt) and ruthenium (Ru) concentrated in the shell, and the other constituents, tungsten (W), and titanium (Ti), concentrated in the core.


Using an atomically-thin coating of noble metal over a tiny particle made of a much more abundant and inexpensive material, MIT engineers have developed new nanoparticle catalysts that could reduce need for precious metals.
Materials that speed up a chemical reaction without getting consumed in the process, known as catalysts, lie at the heart of many technologies, from vehicle emissions-control systems to high-tech devices such as fuel cells and electrolyzers. Unfortunately, catalysts are often pricey because they typically contain one or more noble metals, such as platinum or palladium, whose supplies are limited.
Now, researchers at MIT have found a potential end-run around this limitation: a way to get the same amount of catalytic activity with as little as one-tenth the amount of precious metal.
The key is to use an atomically-thin coating of noble metal over a tiny particle made of a much more abundant and inexpensive material: a kind of ceramic called transition metal carbide. While this idea has been the subject of extensive research, nobody had been able to find a way to get the coating to adhere to the underlying material, until now. And as a bonus, the coated particles actually outperform conventional catalysts (made completely of noble metal nanoparticles), providing greater longevity and better resistance to many unwanted phenomena that plague traditional noble metal catalysts.
The new finding is being reported this week in the journal Science, in a paper by MIT doctoral student Sean Hunt, postdocs Maria Milina and Christopher Hendon, and Associate Professor Yuriy Román-Leshkov of the Department of Chemical Engineering.
Since only the surface of catalytic particles is involved in accelerating a reaction, substituting the bulk of the particle with an inexpensive core can lead to drastic reductions in noble metal use without sacrificing performance.
MIT Researchers Develop New Nanoparticle Catalysts
A simulation of the core-shell structure shows the arrangement of the different elements as they have separated themselves into the two regions.
“For a long time, many researchers have been trying to find ways to make stable coatings of noble metals over earth-abundant cores,” Román-Leshkov says. “There has been some success using metallic cores like nickel and cobalt, but the particles are not stable over long periods of time and end up alloying with the noble metal shell.” Carbides, on the other hand, are resistant to corrosion and clustering, and also cannot alloy with noble metals, making them ideal core candidates.
But noble metals – which get their name from their general reluctance to take part in any kind of chemical activity – don’t easily bond with other materials, so producing coatings from them has been an elusive goal. At the same time, transition metal carbides are extremely difficult to engineer into nanoparticles with controlled properties. This is because they need high temperatures to force carbon into the metal lattice, which leads to particle clumping and surfaces contaminated with excess carbon layers.
The key breakthrough, Hunt says, was to encapsulate the shell and core material precursors into a template made from silica. “This keeps them close together during the heat treatment, making them self-assemble into core-shell structures, conveniently solving both challenges at the same time,” he says. The silica template could then be dissolved away using a simple room-temperature acidic treatment.
In addition to greatly reducing the amount of precious metal required, the process turned out to have other important benefits as well.
“We found that the self-assembly process is very general,” says Hunt. “The reluctance of noble metals to bind to other materials means we could self-assemble incredibly complex catalytic designs with multiple precious metal elements present in the shell and multiple inexpensive elements present in the carbide core.” This allowed the researchers to fine-tune the properties of the catalysts for different applications.
For instance, using a nanoparticle with a platinum and ruthenium shell coating a carbide core made of tungsten and titanium, they designed a highly active and stable catalyst for possible applications in direct methanol fuel cells. After the catalyst was put through 10,000 electrochemical cycles, the new design still performed 10 times better than conventional nanoparticles after similar cycling.
Yet another gain is that these nanoparticles are highly resistant to a problem that can plague other forms of noble-metal catalysts: “poisoning” of the surface by carbon monoxide. “This molecule can drastically curtail the performance of conventional catalysts by bonding to their surface and blocking further interaction, but on the core-shell catalysts, the carbon monoxide detaches more easily,” Román-Leshkov says. While traditional hydrogen fuel cell catalysts can only tolerate 10 parts per million (ppm) of carbon monoxide, the researchers found that their core-shell catalysts could tolerate up to 1,000 ppm.
Lastly, the researchers found that the core-shell structure was stable at high temperatures under various types of reaction conditions, while also remaining resistant to particle clumping. “Whereas in other classes of core-shell nanoparticles the shell dissolves into the core over time, noble metal shells are insoluble in carbide cores,” says Hunt. “This is just another one of the many benefits that ceramic cores can have in designing active and stable catalysts.”
Although work for the translation of the new concept into a commercializable form is still preliminary, in principle it could make a big difference to applications such as fuel cells, where “it would overcome one of the main limitations that fuel cells are facing right now,” Román-Leshkov says, namely the cost and availability of the needed precious metals. In fact, with the assistance of MIT’s Translational Fellows Program, Milina has been focusing on the commercial aspects of the technology, identifying the potential market, value, and customers for these novel materials.
“This is an important discovery regarding the potential applications of core-shell carbide particles coated with precious metal layers,” says Jingguang Chen, a professor of chemical engineering at Columbia University, who was not involved in this work. “It would significantly reduce the amount of precious metals needed, and it could show better catalytic performance due to the synergistic interactions between the precious metal coating and the carbide core,” he says. “Even though these advantages were predicted from previous studies of thin-film model systems, the current study demonstrates the feasibility of potential commercial applications using core shell structures.”
The research team also included Ana Alba-Rubio and James Dumesic at the University of Wisconsin at Madison. The work was supported by the U.S. Department of Energy and the National Science Foundation.
Publication: Sean T. Hunt, et al., “Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts,” Science 20 May 2016: Vol. 352, Issue 6288, pp. 974-978; DOI: 10.1126/science.aad8471
Source: David L. Chandler, MIT News

Monday, 4 July 2016

Google offers new way for users to manage ads, personal data

Google offers new way for users to manage ads, personal data:
Google offers new way for users to manage ads, personal data
This file image provided by Google shows a demonstration of Google's "My Account" mobile search. In 2015, Google opened a "My Account" hub to serve as a one-stop shop for setting privacy and security controls. If they choose, users will now …more
Google is trying to make it easier for you to manage the vast pool of information that it collects about your online activities across phones, computers and other devices.
Among other things, a new privacy tool will enable the more than 1 billion people who use Google's search engine and other services to block certain ads from appearing on every device that they log into, instead of having to make a special request on each individual machine.
Some users of Google's search engine, Gmail and Chrome browser will start receiving notices about the new option beginning Tuesday, but it will take several more weeks before it's available to everyone.
Google also is introducing a "My Activity" feature that will enable users to delete records of their online search requests and videos watched on YouTube in a single location instead of having to visit different websites or apps.
Google's business has been built on its longtime practice of monitoring its users' online behavior in an effort to learn about their interests so it can show ads most likely to appeal to them.
Those customized ads shown alongside Google's search results and the content on millions of other websites have turned Google's corporate parent, Alphabet Inc., into one of the world's most profitable companies.
In an effort to minimize complaints about invading people's privacy, Google has long allowed its users to impose limits on how much data is accumulated about them and how many customized ads they see.
Last year, Google also opened a "My Account" hub to serve as a one-stop shop for setting privacy and security controls.
If they choose, users will now be able to authorize Google to store their web browsing histories in the "My Account" center.
Until now, Google had been keeping personal information in different digital dossiers that sometimes require users to take multiple steps to manage specific pieces of data.
For instance, someone annoyed by a Google-generated ad on their personal computer can prevent it from appearing again by clicking on an "X'' in the corner. Taking that step currently won't block the same ad from appearing on the targeted person's smartphone a few hours later.
Google says that will no longer happen if users allow it to stockpile web browsing histories in the "My Account" center.

Facebook will automatically translate posts into different languages

Facebook will automatically translate posts into different languages:
Facebook plans to use multilingual posts to improve machine translation capabilities with the aim of one day removing language b
Facebook plans to use multilingual posts to improve machine translation capabilities with the aim of one day removing language barriers across the social network
The leading social network first made the "multilingual composer" tool available earlier this year for use on pages representing companies, brands, groups and celebrities through its Pages service.
Now it will be available to general users.
"Page authors and other people on Facebook can compose a single post in multiple languages, and the viewers who speak one of those languages will see the post in their preferred language only—allowing people to more easily interact with their diverse audiences," the company said.
Half of Facebook's more than 1.5 billion users worldwide speaks a language other than English, the California-based social network says.
Among factors Facebook will use to determine which language to use for posts include locales designated in account settings and which languages  routinely use for their posts.
The social network plans to use multilingual posts to improve machine translation capabilities with the aim of one day removing  barriers across the social network.

Sunday, 3 July 2016

Antarctic Ozone Layer Shows Signs of Healing

Antarctic Ozone Layer Shows Signs of Healing:

MIT Scientists Observe First Signs of Healing in the Antarctic Ozone Layer
A simulation of the Antarctic ozone hole, made from data taken on October 22, 2015.
New research details the “first fingerprints of healing” of the Antarctic ozone layer.
Scientists found that the September ozone hole has shrunk by more than 4 million square kilometers — about half the area of the contiguous United States — since 2000, when ozone depletion was at its peak. The team also showed for the first time that this recovery has slowed somewhat at times, due to the effects of volcanic eruptions from year to year. Overall, however, the ozone hole appears to be on a healing path.
The authors used “fingerprints” of the ozone changes with season and altitude to attribute the ozone’s recovery to the continuing decline of atmospheric chlorine originating from chlorofluorocarbons (CFCs). These chemical compounds were once emitted by dry cleaning processes, old refrigerators, and aerosols such as hairspray. In 1987, virtually every country in the world signed on to the Montreal Protocol in a concerted effort to ban the use of CFCs and repair the ozone hole.
“We can now be confident that the things we’ve done have put the planet on a path to heal,” says lead author Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT. “Which is pretty good for us, isn’t it? Aren’t we amazing humans, that we did something that created a situation that we decided collectively, as a world, ‘Let’s get rid of these molecules’? We got rid of them, and now we’re seeing the planet respond.”
Solomon’s co-authors include Diane Ivy, research scientist in the Department of Earth, Atmospheric and Planetary Sciences, along with researchers at the National Center for Atmospheric Research in Boulder, Colorado, and the University of Leeds in the U.K.
Signs before spring
The ozone hole was first discovered using ground-based data that began in the 1950s. Around the mid-1980s, scientists from the British Antarctic survey noticed that the October total ozone was dropping. From then on, scientists worldwide typically tracked ozone depletion using October measurements of Antarctic ozone.
Ozone is sensitive not just to chlorine, but also to temperature and sunlight. Chlorine eats away at ozone, but only if light is present and if the atmosphere is cold enough to create polar stratospheric clouds on which chlorine chemistry can occur — a relationship that Solomon was first to characterize in 1986. Measurements have shown that ozone depletion starts each year in late August, as Antarctica emerges from its dark winter, and the hole is fully formed by early October.
Solomon and her colleagues believed they would get a clearer picture of chlorine’s effects by looking earlier in the year, at ozone levels in September, when cold winter temperatures still prevail and the ozone hole is opening up. The team showed that as the chlorine has decreased, the rate at which the hole opens up in September has slowed down.
“I think people, myself included, had been too focused on October, because that’s when the ozone hole is enormous, in its full glory,” Solomon says. “But October is also subject to the slings and arrows of other things that vary, like slight changes in meteorology. September is a better time to look because chlorine chemistry is firmly in control of the rate at which the hole forms at that time of year.  That point hasn’t really been made strongly in the past.”
A healing trend
The researchers tracked the yearly opening of the Antarctic ozone hole in the month of September, from 2000 to 2015. They analyzed ozone measurements taken from weather balloons and satellites, as well as satellite measurements of sulfur dioxide emitted by volcanoes, which can also enhance ozone depletion. And, they tracked meteorological changes, such as temperature and wind, which can shift the ozone hole back and forth.
They then compared their yearly September ozone measurements with model simulations that predict ozone levels based on the amount of chlorine that scientists have estimated to be present in the atmosphere from year to year. The researchers found that the ozone hole has declined compared to its peak size in 2000, shrinking by more than 4 million square kilometers by 2015. They further found that this decline matched the model’s predictions, and that more than half the shrinkage was due solely to the reduction in atmospheric chlorine.
“It’s been interesting to think about this in a different month, and looking in September was a novel way,” Ivy says. “It showed we can actually see a chemical fingerprint, which is sensitive to the levels of chlorine, finally emerging as a sign of recovery.”
The team did observe an important outlier in the trend: In 2015, the ozone hole reached a record size, despite the fact that atmospheric chlorine continued to drop. In response, scientists had questioned whether any healing could be determined. Going through the data, however, Solomon and her colleagues realized that the 2015 spike in ozone depletion was due primarily to the eruption of the Chilean volcano Calbuco. Volcanoes don’t inject significant chlorine into the stratosphere but they do increase small particles, which increase the amount of polar stratospheric clouds with which the human-made chlorine reacts.
“Why I like this paper so much is, nature threw us a curveball in 2015,” says Ross Salawitch, professor of chemistry and biochemistry at the University of Maryland. “People thought we set a record for the depth of the ozone hole in October 2015. The Solomon paper explains it was due to a specific volcanic eruption. So without this paper, if all we had was the data, we would be scratching our heads — what was going on in 2015?”
As chlorine levels continue to dissipate from the atmosphere, Solomon sees no reason why, barring future volcanic eruptions, the ozone hole shouldn’t shrink and eventually close permanently by midcentury.
“What’s exciting for me personally is, this brings so much of my own work over 30 years full circle,” says Solomon, whose research into chlorine and ozone spurred the Montreal Protocol. “Science was helpful in showing the path, diplomats and countries and industry were incredibly able in charting a pathway out of these molecules, and now we’ve actually seen the planet starting to get better. It’s a wonderful thing.”
This research was supported, in part, by the National Science Foundation and the U.S. Department of Energy.
Publication: Susan Solomon, et al., “Emergence of healing in the Antarctic ozone layer,” Science, 30 Jun 2016; DOI: 10.1126/science.aae0061
Source: Jennifer Chu, MIT News

This drug really could make you — here's why you can't take it yet

This drug really could make you, here's why you can't take it yet:
pill medicineSkye Gould/Tech Insider
There are several things you can do right now to clear up brain fog that makes it hard to keep up with everything you have to get done.
You could go for a run or hit the gym — exercise has been shown to effectively boost cognitive ability. You could get a good night's sleep, something that refreshes energy levels, is essential for memory, and makes it significantly easier to focus. You could have a cup of coffee andbenefit from that proven little helper, caffeine.
But sometimes none of that seems like enough. It makes you want an additional solution, a pill that can boost you for long enough to get you over that hump.
While students and overworked employees frequently experiment with substances like Adderall or Ritalin in an attempt to do just that, it hasn't been shown that most of these "cognitive enhancers" actually make anyone's brain work "better."
But there's one substance that a recent review published in the journal European Neuropsychopharmacology found actually does improve attention, memory, learning, and other cognitive abilities — modafinil. 
Pharmaceutical cognitive enhancement isn't a new idea. People have used drugs to try to boost their brainpower for more than 100 years. Early in his career in the late 1800s, Sigmund Freud experimented prolifically with cocaine, which he described at the time as his "most gorgeous excitement." Mathematician Paul Erdős had such a serious relationship with amphetamines that when he once stopped taking them for a month to win a $500 bet, he immediately got back on drugs afterwards. He famously told the friend he bet: "You've set mathematics back a month."
Those substances, however, come with significant negative side effects. That's what makes modafinil so interesting.
In their review of the literature on modafinil, Oxford researchers Ruairidh Battleday and Anna-Katherine Brem found that it didn't seem to have any particularly serious side effects and didn't seem likely to cause dependency — though there are still unanswered questions there.

How modafinil affects your brain

Battleday and Brem reviewed 24 studies that assessed how modafinil affected healthy non-sleep deprived people's minds (they considered 267 studies, but rejected those that weren't placebo controlled, used unhealthy subjects, or tested animals and not people). The fact that subjects were healthy is an important distinction — many of the ways we look at drugs that affect thinking ability are designed to assess people with cognitive deficiencies.
Most studies could be broken down into either "basic" or "complex" tests of cognitive function, Brem and Battleday tell Tech Insider.
Basic tests assess just one sub-component of cognition and tend to be very simple tasks. On these tests, the effects of modafinil were mixed. It was on complex tests that the authors found consistent improvement, especially in terms of attention, the ability to focus on a task and process relevant information; learning and memory; and executive function, which includes the ability to take in information and use it to come up with plans or strategies.
lucy scarlett johanssonFilms where characters suddenly gain access to new mental powers take the idea to an extreme, but cognitive enhancement is a real possibility. Universal
These complex tasks are much better ways to answer the question of "does this substance actually improve cognitive ability" than the basic ones, the authors tell Tech Insider.
"Rarely in life do we spend an entire day using a sole cognitive sub-domain – attention, for example. Rather, we constantly plan, predict, and problem solve – all of which involve marshaling subdomains of cognition and integrating their output – over varying tasks and difficulties," they wrote in an email. "It is in this sense that complex tasks can approximate everyday functioning better than simple."
As for how modafinil works, we still really don't know. It was originally designed as a treatment for narcolepsy to keep people awake. But no one is entirely certain how it affects cognition.
brainMatt Cardy/Getty
"The best idea we have is that by directly altering the concentration of a group of chemicals in the brain – called 'catecholamines' – modafinil upregulates activity in attention and executive control networks in the brain," the authors tell Tech Insider. "These changes are then hypothesized to allow individuals to perform better on cognitive tasks: particularly those requiring good focus and problem solving."

Can I take it?

So, will your doctor write you a modafinil prescription?
The answer for now is no, unless you have narcolepsy. But that may not always be the case.
When it comes to safety, Brem and Battleday said that the studies they reviewed didn't note serious side effects. 
Most studies reported a slight boost to positive mood and no adverse effects. In the studies that found adverse effects, a small number of participants reported insomnia, headache, stomach ache or nausea, and dry mouth.
That may not sound great, but in context, those effects aren't such a big deal. That's essentially like having an extra cup of coffee that you didn't need, UCLA clinicalpsychiatrist James McGough told The Atlantic's Olga Khazan.
Only one study assessed the potential for abuse, and reported that it was low.
Adderall pills on magazineSubstances like Adderall have a higher risk of abuse. Alex Dodd/flickr
But none of these studies tested long term use, so we don't know if it's safe for someone to take modafinil over an extended period of time. As the authors point out, most of these studies only tested one single dose, which comes nowhere close to assessing risks of regular use. 

Funding is scarce for drugs that help healthy people

Interestingly, Battleday and Brem point out that there isn't much research on cognitive enhancement for healthy people and that there's a lack of funding and perhaps even a bit of a taboo on studying the topic.
"It appears that funding for drug-based studies on healthy individuals fails to attract typically medical-oriented grants and awards," they say.
That's why they say it was hard to find good complex tests of cognitive enhancement, and they hope that perhaps their work will encourage researchers to further investigate the topic. 
If that does happen, there may be surprises out there — perhaps some of the other drugs used for cognitive improvement, things like Adderall, work better for healthy people than we think they do despite their potential dependency risks.
But even if modafinil were to be proven safe long term and its cognitive boosting ability affirmed by further studies, there are still reasons why — for now — doctors aren't going to start prescribing it to healthy people.
At the recent annual meeting of the American Medical Association, the group decided to adopt a policy "discouraging the nonmedical use of prescription drugs for cognitive enhancement in healthy individuals."
nootroboxThere's little evidence so far that tells us how effective many other nootropics are or are not. Dylan Love
Of prescription stimulants, they say that the cognitive effects appear limited for healthy people. Of other supplements and "smart drugs," known as nootropics, they say that there's limited research right now and that more analysis is needed before anyone can conclude that they are safe. 
So don't expect a modafinil prescription soon. Not that that stops many users. There are healthy internet communities dedicated to nootropics, and plenty of user reports on modafinil specifically.
Most of those users order it off the internet from somewhat-shady pharmacies, a practicestrongly discouraged by law enforcement, since it's illegal and potentially dangerous.

Will you someday be able to take the smart pill?

Let's say it turns out that multiple studies show that it's safe to take modafinil occasionally over long periods of time — for the rest of your life, even. Let's say that there are no additional negative side effects that come with that use.
If that's the case, should you be able to use the drug?
"That is a very interesting question, and one society must properly address in the near future; not just for modafinil, but for all potential neuroenhancement agents," say Battleday and Brem. But they point out that even if something proves to be safe for an individual, that doesn't answer all questions about how its use affects the rest of society.
brain computer interfaceA number of other devices might be able to stimulate the brain as well. REUTERS/ Morris MacMatzen
Some people fear that if we permit any use of cognitive enhancing drugs for individuals, it will eventually lead to people being required to use those substances, even if they don't want to. That could be due to internal pressure that comes from a fear of keeping up — if my co-workers are taking this brain-boosting drug and I'm not, will I be judged as not working hard enough? 
There's even a concern that people in certain professions might be compelled to use brain-enhancing substances. Could we get to the point that it's considered unsafe for pilots to fly or surgeons to operate without using focus- and attention-boosting drugs? 
In The Conversation, researchers Emma Jane and Nicole Vincent describe how the use of beta-blockers became widespread among classical musicians. While some people first used these drugs to get over performance anxiety, they were so effective and had minimal enough side effects that other musicians felt they were losing out by not using beta-blockers as well.
"Just as the use of beta blockers has become widespread in the classical music scene, so too cognitive enhancement threatens to become a new 'normal', a de facto standard that pressures everyone to bio-hack their brains to keep up," they write.
And the ethical questions don't stop there. There are questions about justice — if wealthy people can easily afford cognitive enhancement but no one else can, that's likely to create an even more unequal society. 
Cognitive enhancing substances are already out there and more are likely to become available in the near future. These questions about how to use them or how to regulate them are important.
"This is not a future but already a present scenario," say Brem and Battleday. 

Saturday, 2 July 2016

New Hydrogel Hybrid Could Be Used To Make Artificial Skin

New Hydrogel Hybrid Could Be Used To Make Artificial Skin:
MIT Develops Tough Hydrogel Hybrid
MIT engineers have developed a method to bind gelatin-like polymer materials called hydrogels and elastomers, which could be used to make artificial skin and longer-lasting contact lenses.
If you leave a cube of Jell-O on the kitchen counter, eventually its water will evaporate, leaving behind a shrunken, hardened mass — hardly an appetizing confection. The same is true for hydrogels. Made mostly of water, these gelatin-like polymer materials are stretchy and absorbent until they inevitably dry out.
Now engineers at MIT have found a way to prevent hydrogels from dehydrating, with a technique that could lead to longer-lasting contact lenses, stretchy microfluidic devices, flexible bioelectronics, and even artificial skin.

See how MIT researchers designed a hydrogel that doesn’t dry out. Video: Melanie Gonick/MIT
The engineers, led by Xuanhe Zhao, the Robert N. Noyce Career Development Associate Professor in MIT’s Department of Mechanical Engineering, devised a method to robustly bind hydrogels to elastomers — elastic polymers such as rubber and silicone that are stretchy like hydrogels yet impervious to water. They found that coating hydrogels with a thin elastomer layer provided a water-trapping barrier that kept the hydrogel moist, flexible, and robust. The results are published in the journal Nature Communications.
Zhao says the group took inspiration for its design from human skin, which is composed of an outer epidermis layer bonded to an underlying dermis layer. The epidermis acts as a shield, protecting the dermis and its network of nerves and capillaries, as well as the rest of the body’s muscles and organs, from drying out.
The team’s hydrogel-elastomer hybrid is similar in design to, and in fact multiple times tougher than, the bond between the epidermis and dermis. The team developed a physical model to quantitatively guide the design of various hydrogel-elastomer bonds. In addition, the researchers are exploring various applications for the hybrid material, including artificial skin. In the same paper, they report inventing a technique to pattern tiny channels into the hybrid material, similar to blood vessels. They have also embedded complex ionic circuits in the material to mimic nerve networks.
“We hope this work will pave the way to synthetic skin, or even robots with very soft, flexible skin with biological functions,” Zhao says.
The paper’s lead author is MIT graduate student Hyunwoo Yuk. Co-authors include MIT graduate students German Alberto Parada and Xinyue Liu and former Zhao group postdoc Teng Zhang, now an assistant professor at Syracuse University.
MIT Develops Tough New Hydrogel Hybrid
Figure (a) shows the fabrication procedure for a hydrogel-elastomer microfluidic chip. Figure (b) shows that the hydrogel-elastomer microfluidic hybrid supports convection of chemicals (represented by food dye in different colors) in the microfluidic channels and diffusion of chemicals in the hydrogel, even when the material is stretched, as seen in figure (c). In figure (d), the microfluidic hybrid is used as a platform for a diffusion-reaction study. Acid and base solutions from two microfluidic channels diffuse in the pH-sensitive hydrogel and form regions of different colors (light red for acid and dark violet for base).
Getting under the skin
In December 2015, Zhao’s team reported that they had developed a technique to achieve extremely robust bonding of hydrogels to solid surfaces such as metal, ceramic, and glass. The researchers used the technique to embed electronic sensors within hydrogels to create a “smart” bandage. They found, however, that the hydrogel would eventually dry out, losing its flexibility.
Others have tried to treat hydrogels with salts to prevent dehydration, which Zhao says is effective, but this method can make a hydrogel incompatible with biological tissues. Instead, the researchers, inspired by skin, reasoned that coating hydrogels with a material that was similarly stretchy but also water-resistant would be a better strategy for preventing dehydration. They soon landed on elastomers as the ideal coating, though the rubbery material came with one major challenge: It was inherently resistant to bonding with hydrogels.
“Most elastomers are hydrophobic, meaning they do not like water,” Yuk says. “But hydrogels are a modified version of water. So these materials don’t like each other much and usually can’t form good adhesion.”
The team tried to bond the materials together using the technique they developed for solid surfaces, but with elastomers, Yuk says, the hydrogel bonding was “horribly weak.” After searching through the literature on chemical bonding agents, the researchers found a candidate compound that might bring hydrogels and elastomers together: benzophenone, which is activated via ultraviolet (UV) light.
After dipping a thin sheet of elastomer into a solution of benzophenone, the researchers wrapped the treated elastomer around a sheet of hydrogel and exposed the hybrid to UV light. They found that after 48 hours in a dry laboratory environment, the weight of the hybrid material did not change, indicating that the hydrogel retained most of its moisture. They also measured the force required to peel the two materials apart, and found that to separate them required 1,000 joules per square meters — much higher than the force needed to peel the skin’s epidermis from the dermis.
“This is tougher even than skin,” Zhao says. “We can also stretch the material to seven times its original length, and the bond still holds.”
Expanding the hydrogel toolset
Taking the comparison with skin a step further, the team devised a method to etch tiny channels within the hydrogel-elastomer hybrid to simulate a simple network of blood vessels. They first cured a common elastomer onto a silicon wafer mold with a simple three-channel pattern, etching the pattern onto the elastomer using soft lithography. They then dipped the patterned elastomer in benzophenone, laid a sheet of hydrogel over the elastomer, and exposed both layers to ultraviolet light. In experiments, the researchers were able to flow red, blue, and green food coloring through each channel in the hybrid material.
Yuk says in the future, the hybrid-elastomer material may be used as a stretchy microfluidic bandage, to deliver drugs directly through the skin.
“We showed that we can use this as a stretchable microfluidic circuit,” Yuk says. “In the human body, things are moving, bending, and deforming. Here, we can perhaps do microfluidics and see how [the device] behaves in a moving part of the body.”
The researchers also explored the hybrid material’s potential as a complex ionic circuit. A neural network is such a circuit; nerves in the skin send ions back and forth to signal sensations such as heat and pain. Zhao says hydrogels, being mostly composed of water, are natural conductors through which ions can flow. The addition of an elastomer layer, he says, acts as an insulator, preventing ions from escaping — an essential combination for any circuit.
To make it conductive to ions, the researchers submerged the hybrid material in a concentrated solution of sodium chloride, then connected the material to an LED light. By placing electrodes at either end of the material, they were able to generate an ionic current that switched on the light.
“We show very beautiful circuits not made of metal, but of hydrogels, simulating the function of neurons,” Yuk says. “We can stretch them, and they still maintain connectivity and function.”
Syun-Hyun Yun, an associate professor at Harvard Medical School and Massachusetts General Hospital, says that hydrogels and elastomers have distinct physical and chemical properties that, when combined, may lead to new applications.
“It is a thought-provoking work,” says Yun, who was not involved in the research. “Among many [applications], I can imagine smart artificial skins that are implanted and provide a window to interact with the body for monitoring health, sensing pathogens, and delivering drugs.”
Next, the group hopes to further test the hybrid material’s potential in a number of applications, including wearable electronics and on-demand drug-delivering bandages, as well as nondrying, circuit-embedded contact lenses.
“Ultimately, we’re trying to expand the argument of using hydrogels as an advanced engineering toolset,” Zhao says.
This research was funded, in part, by the Office of Naval Research, Draper Laboratory, MIT Institute for Soldier Nanotechnologies, and National Science Foundation.
Publication: Hyunwoo Yuk, et al., “Skin-inspired hydrogel–elastomer hybrids with robust interfaces and functional microstructures,” Nature Communications 7, Article number: 12028 doi:10.1038/ncomms12028
Source: Jennifer Chu, MIT News