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Topics - Mostakima Mafruha Lubna

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Through a combination of data analysis and numerical modeling work, researchers have found a record of the ancient Moon-forming giant impact observable in stony meteorites. Their work will appear in the April 2015 issue of the Journal Science. The work was done by NASA Solar System Exploration Research Virtual Institute (SSERVI) researchers led by Principal Investigator Bill Bottke of the Institute for the Science of Exploration Targets (ISET) team at the Southwest Research Institute and included Tim Swindle, director of the University of Arizona's Lunar and Planetary Laboratory.

The inner Solar System's biggest known collision was the Moon-forming giant impact between a large protoplanet and the proto-Earth. The timing of this giant impact, however, is uncertain, with the ages of the most ancient lunar samples returned by the Apollo astronauts still being debated. Numerical simulations of the giant impact indicate this event not only created a disk of debris near Earth that formed the Moon, but it also ejected huge amounts of debris completely out of the Earth-Moon system. The fate of this material, comprising as much as several percent of an Earth mass, has not been closely examined until recently. However, it is likely some of it blasted main belt asteroids, with a record plausibly left behind in their near-surface rocks. Collisions on these asteroids in more recent times delivered these shocked remnants to Earth, which scientists have now used to date the age of the Moon.

The research indicates numerous kilometer-sized fragments from the giant impact struck main belt asteroids at much higher velocities than typical main belt collisions, heating the surface and leaving behind a permanent record of the impact event. Evidence that the giant impact produced a large number of kilometer-sized fragments can be inferred from laboratory and numerical impact experiments, the ancient lunar impact record itself, and the numbers and sizes of fragments produced by major main belt asteroid collisions.

Once the team concluded that pieces of the Moon-forming impact hit main belt asteroids and left a record of shock heating events in some meteorites, they set out to deduce both the timing and the relative magnitude of the bombardment. By modeling the evolution of giant impact debris over time and fitting the results to ancient impact heat signatures in stony meteorites, the team was able to infer the Moon formed about 4.47 billion years ago, in agreement with many previous estimates. The most ancient Solar System materials found in meteorites are about one hundred million years older than this age.

Insights into the last stages of planet formation in the inner solar system can be gleaned from these impact signatures. For example, the team is exploring how they can be used to place new constraints on how many asteroid-like bodies still existed in the inner Solar System in the aftermath of planet formation. They can also help researchers deduce the earliest bombardment history of ancient bodies like Vesta, one of the targets of NASA's Dawn mission and a main belt asteroid whose fragments were delivered to Earth in the form of meteorites. It is even possible that tiny remnants of the Moon-forming impactor or proto-Earth might still be found within meteorites that show signs of shock heating by giant impact debris. This would allow scientists to explore for the first time the unknown primordial nature of our homeworld.

Co-author Swindle, who specializes in finding the times when meteorites or lunar samples were involved in large collisions, said: "Bill Bottke had the idea of looking at the asteroid belt to see what effect a Moon-forming giant impact would have, and realized that you would expect a lot of collisions in the period shortly after that.

"Here at LPL, we had been determining ages of impact events that affected meteorites, and when we got together, we found that our data matched his predictions," he added. "It's a great example of taking advantage of groups that work in two different specialties - orbital dynamics and chronology - and combining their expertise."

Intriguingly, some debris may have also returned to hit the Earth and Moon after remaining in solar orbit over timescales ranging from tens of thousands of years to 400 million years.

"The importance of giant impact ejecta returning to strike the Moon could also play an intriguing role in the earliest phase of lunar bombardment," said Bottke, who is an alumnus of the University of Arizona's Lunar and Planetary Laboratory. "This research is helping to refine our time scales for 'what happened when' on other worlds in the Solar System."

Yvonne Pendleton, Director of the NASA SSERVI Institute, notes: "This is an excellent example of the power of multidisciplinary science. By linking studies of the Moon, of main belt asteroids, and of meteorites that fall to Earth, we gain a better understanding of the earliest history of our Solar System."

### This research was supported in part by NASA's Solar System Exploration Research Virtual Institute (SSERVI) at NASA's Ames Research Center in Moffett Field, California. SSERVI is funded by the Science Mission Directorate and Human Exploration and Operations Mission Directorate at NASA Headquarters to enable cross-team and interdisciplinary research that pushes forward the boundaries of science and exploration.

Environmental Science and Disaster Management / Do Black Holes Die?
« on: April 21, 2015, 04:05:46 PM »
Black holes are enormous cosmic bodies with immense gravitational pull. Over time black holes keep sucking in matter around it and keep getting bigger and bigger.  Do black holes die or continue for ever ? As black hole feed on matter, principles of quantum mechanics eventually lead to demise of black holes.

In quantum mechanics, subatomic positive and negative particles are continuously created and annihilated into energy. At times when these particles are created at event horizon gravity of black hole pull in negative particles while positive particles end up escaping into the space. This phenomena was first described by Stephen Hawking thus also known Hawking’s radiation. Over time, the black hole emits energy in from of positive particles leading to lose of mass. Black holes will continue to loss its mass and eventually evaporate to nothing and/or they may become unstable cosmic bodies eventually ending with explosive gamma rays bursts.

New studies by astronomers are slowly throwing some light on dark matter, the invisible and mysterious stuff that scientists believe makes up much of the universe. For the first time, astronomers believe they've observed the interactions of dark matter via a factor other than the force of gravity.

Dark matter's gravitational interactions with the parts of the universe that we can actually see are the only reason that we know it exists at all. Weirdly, it has seemed until now that dark matter has no other known interactions with anything in the universe, including itself. A recent study seemed to back up the notion that bits of dark matter appear to just drift through space, and not even interact with each other.

However, new observations of the simultaneous collision of four galaxies in the galaxy cluster Abell 3827 – using the European Southern Observatory's Very Large Telescope (VLT) in Chile and a technique called "gravitational lensing" – seemed to show a "clump" of dark matter around one of the galaxies, lagging a bit behind that galaxy.

This sort of lollygagging is something that scientists have predicted might be observable during collisions if dark matter were to interact with itself through some force other than gravity, even slightly.

"We used to think that dark matter just sits around, minding its own business, except for its gravitational pull," said Richard Massey at Durham University, lead author of a paper on the study. "But if dark matter were being slowed down during this collision, it could be the first evidence for rich physics in the dark sector – the hidden Universe all around us."

Massey was also part of the study from last month which seemed to show that dark matter does interact even with itself at all. The researchers say the new findings do not necessarily conflict with the earlier study, however. That's because the new research looks at the motion of individual galaxies rather than galaxy clusters, along with the fact that collisions between them may have lasted longer, allowing a small frictional force to build up over a time span lasting between "only" 100 million years to about a billion years.

Massey believes that when looked at together, the two studies may actually work to put limits on the behavior of dark matter. "We are finally homing in dark matter from above and below – squeezing our knowledge from two directions," he said. "Dark matter, we’re coming for you."

The research paper was recently published in the journal Monthly Notices of the Royal Astronomical Society. Source: ESO

One of the biggest questions to date pertains to the expansion of the universe since the “Big Bang”. While some believe the universe is expanding rapidly, still others think the universe is moving outward at a much slower pace. Which idea is correct?

Fast or slow The basic idea that the universe is expanding at a rapid pace comes from observation of supernovae. Different types of supernovae have been found, for instance, type Ia supernovae, which are uniform and used as beacons to probe the outer reaches of space. Peter Milne of the Department of Astronomy and Steward Observatory reported that supernovae are found in many different populations with varying degrees of brightness. This poses many questions following. “Differences in brightness are not random. There are two categories of supernovae: the nearby minority and the distant majority stars,” said Milne. According to the idea of consistent growth, previous assumptions say that supernovae are the same whether near or far, moving at the same rate of expansion. This could be false. Contrary to previous belief, signs point to a recent rapid expansion.
The popular idea of a rapidly expanding universe The view of the fast bursting universe resulted in the 2011 Nobel Prize in Physics granted to Brian P. Schmidt and three other scientists. They all believed that dim stars signified supernovae which moved farther away from the other stars, much farther than they should, and at a faster pace. This is what stemmed the belief that the speed that galaxies move away from each other is increasing. “Many scientists use the type la supernovae as a guidepost. Type Ia supernovae are all similar-shine equally bright after they explode- than other stars in the galaxy. Since they should be the same as other stars, but are not, scientists assume they are farther away, pushed by rapid expansion,” says Milne.
Observations Observations from The Hubble Space Telescope and NASA’s Swift Satellite were used to study type Ia supernovae in ultraviolet and visible light. Milne, together with Ryan J. Foley of the University of Illinois-Urbana Campaign, Gautham Narayan of the National Optical Astronomy Observatory of Tucson and Peter J. Brown of Texas A&M collected crucial data with these instruments. Differences between the shifts from blue to red or vice versa (indicating different populations of supernovae) were followed by observations in the ultraviolet light. “Results are great!” Says Neil Gehrels investigator of the Swift Satellite. “This shows how our satellite can respond to new phenomenon in a quick manner.”

xtreme success results from an extreme personality and comes at the cost of many other things. Extreme success is different from what I suppose you could just consider 'success', so know that you don't have to be Richard or Elon to be affluent and accomplished and maintain a great lifestyle. Your odds of happiness are better that way. But if you're extreme, you must be what you are, which means that happiness is more or less beside the point. These people tend to be freaks and misfits who were forced to experience the world in an unusually challenging way. They developed strategies to survive, and as they grow older they find ways to apply these strategies to other things, and create for themselves a distinct and powerful advantage. They don't think the way other people think. They see things from angles that unlock new ideas and insights. Other people consider them to be somewhat insane.
e obsessed.

Be obsessed.

Be obsessed.

If you're not obsessed, then stop what you're doing and find whatever does obsess you. It helps to have an ego, but you must be in service to something bigger if you are to inspire the people you need to help you  (and make no mistake, you will need them). That 'something bigger' prevents you from going off into the ether when people flock round you and tell you how fabulous you are when you aren't and how great your stuff is when it isn't. Don't pursue something because you "want to be great". Pursue something because it fascinates you, because the pursuit itself engages and compels you. Extreme people combine brilliance and talent with an *insane* work ethic, so if the work itself doesn't drive you, you will burn out or fall by the wayside or your extreme competitors will crush you and make you cry.
Follow your obsessions until a problem starts to emerge, a big meaty challenging problem that impacts as many people as possible, that you feel hellbent to solve or die trying. It might take years to find that problem, because you have to explore different bodies of knowledge, collect the dots and then connect and complete them.

It helps to have superhuman energy and stamina. If you are not blessed with godlike genetics, then make it a point to get into the best shape possible. There will be jet lag, mental fatigue, bouts of hard partying, loneliness, pointless meetings, major setbacks, family drama, issues with the Significant Other you rarely see, dark nights of the soul, people who bore and annoy you, little sleep, less sleep than that. Keep your body sharp to keep your mind sharp. It pays off.

Learn to handle a level of stress that would break most people.
Don't follow a pre-existing path, and don't look to imitate your role models. There is no "next step". Extreme success is not like other kinds of success; what has worked for someone else, probably won't work for you. They are individuals with bold points of view who exploit their very particular set of unique and particular strengths. They are unconventional, and one reason they become the entrepreneurs they become is because they can't or don't or won't fit into the structures and routines of corporate life. They are dyslexic, they are autistic, they have ADD, they are square pegs in round holes, they piss people off, get into arguments, rock the boat, laugh in the face of paperwork. But they transform weaknesses in ways that create added advantage -- the strategies I mentioned earlier -- and seek partnerships with people who excel in the areas where they have no talent whatsoever.

They do not fear failure -- or they do, but they move ahead anyway. They will experience heroic, spectacular, humiliating, very public failure but find a way to reframe until it isn't failure at all. When they fail in ways that other people won't, they learn things that other people don't and never will. They have incredible grit and resilience.
They are unlikely to be reading stuff like this. (This is *not* to slam or criticize people who do; I love to read this stuff myself.) They are more likely to go straight to a book: perhaps a biography of Alexander the Great or Catherine the Great* or someone else they consider Great. Surfing the 'Net is a deadly timesuck, and given what they know their time is worth -- even back in the day when technically it was not worth that -- they can't afford it.

I could go on, it's a fascinating subject, but you get the idea. I wish you luck and strength and perhaps a stiff drink should you need it.

Steve Jobs wouldn't, and for good reason too.

In a Sunday article, New York Times reporter Nick Bilton said he once assumingly asked Jobs, “So your kids must love the iPad?”

Jobs responded: “They haven't used it. We limit how much technology our kids use at home.”

Especially in Silicon Valley, there is actually a trend of tech execs and engineers who shield their kids from technology. They even send their kids to non-tech schools like the Waldorf School in Los Altos, where computers aren't found anywhere because they only focus on hands-on learning.

There is a quote that was highlighted in The Times by Chris Anderson, CEO of 3D Robotics and a father of five. He explains what drives those who work in tech to keep it from their kids.

“My kids accuse me and my wife of being fascists and overly concerned about tech, and they say that none of their friends have the same rules… That's because we have seen the dangers of technology firsthand. I've seen it in myself, I don't want to see that happen to my kids.”

If our current addictions to our iPhones and other tech is any indication, we may be setting up our children for incomplete, handicapped lives devoid of imagination, creativity and wonder when we hook them onto technology at an early age. We were the last generation to play outside precisely because we didn't have smartphones and laptops. We learned from movement, hands-on interaction, and we absorbed information through books and socialization with other humans as opposed to a Google search.

Learning in different ways has helped us become more well-rounded individuals — so, should we be more worried that we are robbing our children of the ability to Snapchat and play “Candy Crush” all day if we don't hand them a smartphone, or should we more worried that we would be robbing them of a healthier, less dependent development if we do hand them a smartphone? I think Steve Jobs had it right in regard to his kids.

So the next time you think about how you will raise your kids, you may want to (highly) consider not giving them whatever fancy tech we'll have while they are growing up. Play outside with them and surround them with nature; they might hate you, but they will absolutely thank you for it later, because I'm willing to bet that's exactly how many of us feel about it now that we are older.

Despite significant progress in medical treatments of severe burn wounds, infection and subsequent sepsis persist as frequent causes of morbidity and mortality for burn victims. This is due not only to the extensive compromise of the protective barrier against microbial invasion, but also as a result of growing pathogen resistance to therapeutic options.
Innovative therapies are urgently needed that overcome mechanisms of pathogen resistance – not only for thermal injuries but in general – and are easily administered without concerning systemic side effects (read more: "Nanotechnology solutions to combat superbugs").
"Antimicrobial resistance continues to be a growing crisis, highlighted by the FDA's Generating Antibiotic Incentives Now (GAIN) program, through which three new antibiotics with the indication for acute bacterial skin and skin structure infections were rapidly approved in unprecedented succession. All three however are systemically administered, and we have yet to see new topical antimicrobials emerge," Dr Adam Friedman, Assistant Professor of Dermatology and Director of Dermatologic research at the Montefiore-Albert Einstein College of Medicine, tells Nanowerk. "For me, this gap fuels innovation, serving as the inspiration for my research with broad-spectrum, multi-mechanistic antimicrobial nanomaterials."
In new work, Friedman and a team of researchers from Albert Einstein College of Medicine and Oregon State University have explored the use of curcumin nanoparticles for the treatment of infected burn wounds, an application that resulted in reduced bacterial load and enhancing wound healing.

Turmeric (Curcuma longa L.) is the shining star among the cornucopia of traditional medicinal plants. It has a long history of usage in traditional medicine in India and China. Ancient Indians have known the medicinal properties of turmeric – i.e. curcumin – for several millennia.
In the scientific literature there is a large body of evidence showing that curcuminoids exhibit a broad spectrum of biological and pharmacological activities including anti-oxidant, anti-inflammatory, anti-bacterial, anti-fungal, anti-parasitic, anti-mutagen, anti-cancer and detox properties. Curcumin's unique ability to work through so many different pathways with its extraordinary antioxidant and anti-inflammatory attributes can have a positive influence in combating almost every known disease (read more: "Nanotechnology-enhanced curcumin: Symbiosis of ancient wisdom with modern medical science" and, if you are really into details, this: "Nanotechnology-enhanced curcumin - literature and patent analysis").
"There has been tremendous excitement regarding curcumin in multiple fields of medicine, most prominently in Oncology," Friedman points out. "Here, for the first time, we demonstrated that curcumin nanoparticles were more effective at both accelerating thermal burn wound closure and clearing infection with Methicillin Resistant S. aureus (MRSA) as compared to curcumin in its bulk size."
Friedman and his team utilized an innovative sol-gel-based polymerization technique to create silane composite nanoparticles that incorporate curcumin within a highly structured porous lattice. The versatility of the resulting nanoformulation allows for loading of different active ingredients, with therapeutic efficacy when applied topically, intradermally, and intravenously.
"While so much is known about curcumin's therapeutic potential, there have been numerous limitations with respect to clinical translation resulting from its poor solubility, instability at physiology pH and unsightly yellow-orange color," says Friedman. "Nanotechnology can and has overcome many of these impediments. At the nanoscale, the likelihood of curcumin interfacing with its intended target is much greater."
To sum it up, this work nicely demonstrates that curcumin nanoparticle technology circumvents the difficulties inherent in curcumin administration, enabling delivery of this therapeutic substance. Unlike currently used treatments, curcumin nanoparticles are less likely to select for resistant bacterial strains or delay wound healing.
"We believe our technology has the potential to serve as a novel topical agent for burn wound infection and possibly other cutaneous injuries," Friedman concludes.

Ref - © Nanowerk Spotlight

For instance, it has been shown that silver nanoparticles exposed to stomach fluid undergo changes in size, shape, and composition, and the rates of these changes are dependent on particle size (see: "Changes in silver nanoparticles exposed to human synthetic stomach fluid: Effects of particle size and surface chemistry").
But this means that, if size, including the influence of agglomeration/aggregation, can change with environmental conditions, then real-time monitoring of engineered nanomaterial behavior within biological environments will be extremely difficult. Also, numerous preanalysis steps, including degradation of the food matrix and separation of the compounds of interest from background nanomaterials, are required to isolate the nanomaterial for characterization.

What approaches are currently available?
"Due to the complexity and wide chemical and physical disparity of nanomaterials at different points in time from processing to ingestion, it is likely that no single method will suffice to characterize the potential benefits or risks that these materials may present to the consumer," write the authors. "A combination of methods aimed at assessing specific questions will likely be needed to ascertain the best analytical results."
They explain that detection methods differ based on the specific questions being addressed, such as the following:
Are nanoscale materials present, or have they dispersed into their molecular components and therefore ceased to be nanomaterials?
Do the nanoscale materials have a consistent size and shape, or have they become chemically altered due to biological interaction such as aggregation/ disaggregation?
Has there been chemical transformation of some surface or core component (i.e., oxidation or reduction), or is the concentration of some component changing?
Is it necessary to ascertain the amount of nanomaterial present and where exactly the nanomaterial is located, or is it appropriate to ascertain only if it is present?
The article then goes on and details the various detection techniques currently available for various nanomaterials.
Concluding, the author team emphasizes the need for interdisciplinary collaboration in order to allow active sharing of knowledge among chemists, physicists, toxicologists, food technologists, instrument vendors, and other important stakeholders: "Moving beyond the isolation of critical information within individual knowledge domains and stakeholder groups will leverage nanotechnology and the nanoscale from an area of perceived uncertainty and debate into a rich field of potential."

Ref - © Nanowerk

 Nanotechnology, specifically nanomaterial engineering, has begun to find applications in agriculture and the food industry. Some nanomaterials have unique physicochemical properties that can be exploited for beneficial effects on foods, leading to increased shelf life, enhanced flavor release, and increased absorption of nutrients and other bioactive components.
Of course, there seems to be no limit to what food technologists are prepared to do to our food and nanotechnology will give them a whole new set of tools to go to new extremes. In our special Food Nanotechnology section we have prepared an overview of this area.
The ability to detect and to measure a given nanomaterial at key time points in the food lifecycle is critical for estimating the nanoscale properties of interest that dictate manufacturing consistency and safety, as well as understanding potential beneficial or adverse effects from food intercalation.
In a recent perspectives article in ACS Nano ("Measurement of Nanomaterials in Foods: Integrative Consideration of Challenges and Future Prospects"), scientists describe the state of the science for nanoscale measurement methods development as applied to foods and the alimentary tract and, more importantly, to identify the critical methods' knowledge gaps that must be addressed to inform appropriate risk management and public policy.
This article draws from the combined work of experts participating in the NanoRelease Food Additive (NRFA) project, an international multi-stakeholder effort that aims to address method development needs for nanoscale materials currently used in commerce.
Where is the problem?
According to the authors, there are several factors that complicate the development of methods to detect and to measure nanomaterials in foods and food contact materials.
First, whether naturally present or intentionally added to foods, the potential applications and impacts of nanomaterials within these matrices are diverse.
Secondly, it is extremely important to recognize and to differentiate nanoscale materials that are naturally present in the food supply. For instance, prior to industrial processing, dairy products contain a plethora of associated colloids, biopolymeric nanoparticles, and nanoemulsions.
And finally, a considerable characterization challenge includes the consideration of physicochemical changes as a nanomaterial moves from formulation and preparation through incorporation into foods and ultimately through consumption and absorption. These complexities that affect the biological interactions of the nanomaterial could include the effective nanomaterial size (including agglomeration and aggregation), solubility/dispersibility, chemical form, chemical reactivity, surface chemistry, shape, and porosity.
Whereas relatively pristine nanomaterials at the point of their manufacture are fairly straightforward to characterize, these materials undergo physical and/or chemical changes during food processing, packaging, aging, and during their transit through the alimentary tract. Especially this last area – the inherent complexity of the mammalian alimentary tract – creates additional complications for nanomaterial characterization.
As the authors point out, the pH, ionic strength, composition, and absorptive surfaces of the alimentary tract vary considerably, and the composition of the food matrix changes during digestion. In addition, the microflora with which nanoparticles interact may change dramatically in terms of both species and numbers.

Ref - © Nanowerk

There is a general perception that nanotechnologies will have a significant impact on developing 'green' and 'clean' technologies with considerable environmental benefits. The associated concept of green nanotechnology aims to exploit nanotech-enabled innovations in materials science and engineering to generate products and processes that are energy efficient as well as economically and environmentally sustainable. These applications are expected to impact a large range of economic sectors, such as energy production and storage, clean up-technologies, as well as construction and related infrastructure industries.
A recent review article in Environmental Health ("Opportunities and challenges of nanotechnology in the green economy") examines opportunities and practical challenges that nanotechnology applications pose in addressing the guiding principles for a green economy.
The authors provide examples of the potential for nanotechnology applications to address social and environmental challenges, particularly in energy production and storage (read more: "Nanotechnology in Energy") thus reducing pressure on raw materials, clean-up technologies as well as in fostering sustainable manufactured products. The areas covered include:
nanomaterials for energy conversion (photovoltaics, fuel cells, hydrogen storage and transportation)
nanomaterials for energy storage
nanomaterials for water clean-up technologies
nanomaterials for the construction industry

These solutions may offer the opportunities to reduce pressure on raw materials trading on renewable energy, to improve power delivery systems to be more reliable, efficient and safe as well as to use unconventional water sources or nano-enabled construction products therefore providing better ecosystem and livelihood conditions.
Conflicting with this positive message is the growing body of research that raises questions about the potentially negative effects of engineered nanoparticles on human health and the environment. This area includes the actual processes of manufacturing nanomaterials and the environmental footprint they create, in absolute terms and in comparison with existing industrial manufacturing processes (read more: "Not so 'green' nanotechnology manufacturing").
Consequently, the review aims to critically assess the impact that green nanotechnology may have on the health and safety of workers involved in this innovative sector and proposes action strategies for the management of emerging occupational risks.

The authors propose action strategies for the assessment, management and communication of risks aimed to precautionary adopt preventive measures including full lifecycle assessment of nanomaterials (read more: "Evaluation of 'green' nanotechnology requires a full life cycle assessment"), formation and training of employees, collective and personal protective equipment, health surveillance programs to protect the health and safety of nano-workers.

Concluding, the scientists emphasize that green nanotechnology should not only provide green solutions, but should also 'become green' in terms of the attention paid to occupational safety and health. In this context, a full democratic discussion between expertise should be pursued to carefully balance the benefits of green nanotechnology and the potential costs for the society, particularly in terms of environmental, public and occupational health. This careful consideration will maximize environmental and societal benefits, health gains and cost savings and will increase the likelihood of further investment and sustainable development of this promising technological field.
Ref- © Nanowerk

The food chemistry Maillard reaction is responsible for many colors and flavors in foods – roasting of coffee, baking of bread and sizzling of meat. Scientists from National University of Singapore, Ghim Wei Ho and her team, have made use of this ingenious food chemistry to 'cook' their copper nanowires. Naturally, a lingering chocolate-like aroma was detected during the copper nanowires synthesis.
The findings have been reported in the November 7, 2014 online edition of Green Chemistry ("Facile control of copper nanowire dimensions via the Maillard reaction: using food chemistry for fabricating large-scale transparent flexible conductors").
Metallic nanowires, especially cheap and abundant copper nanowires, have huge potential applications in miniaturized interconnects, sensors and transparent conductors featuring solar cells, touch screens and LED displays.
Traditionally, indium tin oxide (ITO) is the most widely used transparent conductor in today’s consumer electronics. However, alternatives are being sought due to the high cost and finite supply of indium.
Films made from copper nanowires are promising candidates, exhibiting high conductivity and optical transparency in addition to being flexible.
Copper nanowires are typically synthesized by the reduction of Cu2+ in solution to its metal form using hydrazine and ethylenediamine – both of which are notoriously hazardous and toxic.
Kevin Moe, the main researcher in this study and the paper's first author, has uncovered a green approach that formulates copper atoms in water to form untangled metallic state nanowires. The thin and length-optimized nanowires can then be transformed into smooth transparent, conductive films that can be easily and quickly transferred virtually onto any substrates – glass, plastic or even superhydrophobic lotus leaves.
The Maillard reaction between amino acids and reducing sugar occurs at approximately 140-165°C. By varying the type and concentration of reducing sugar and amine in the presence of Cu2+, the team has been able to synthesize copper nanowires with a tuneable aspect ratio via a green route for the first time.
Through the addition of glycine, the copper nanowires length could be systematically tuned from several millimeters down to hundreds of microns. Such capability should not be underestimated as it serves to prevent the nanowires from getting irreversibly entangled, allowing excellent nanowire dispersions without the need for surfactants.
The concomitant increase in the nanowires' diameter to ∼150 nm allows improved sheet resistances without compromising optical transparency. The well-dispersed copper nanowires could be coated uniformly regardless of flat or curve geometries and wetting or non-wetting surfaces in every practical sense.

Ref- @Nanowerk Spotlight, Ghim Wei Ho, Associate Professor, Engineering Science, National University of Singapore

Paper has become a popular substrate for fabricating electronics – it is a cheap, abundant material and easy to print on. Electronics printed on paper are inexpensive, flexible, and recyclable, and could lead to applications such as smart labels on foods and pharmaceuticals or as wearable medical sensors. Paper has been used for printed memory, as gas sensors ("Cheap nanotechnology paper-based gas sensors") or bioactive sensor to detect neurotoxins.
Most printed electronics applications rely on some kind of ink formulated with conductive nanomaterials (read more: "Conductive nanomaterials for printed electronics applications"). Researchers have now introduced a rapid and facile method to fabricate a foldable capacitive touch pad using silver nanowire inks.
The international research team has published their findings in the November 3, 2014 online edition of ACS Applied Materials & Interfaces.
"Paper electronics have been extensively studied in the past years but a printing protocol has yet to be developed," Anming Hu, an assistant professor at the University of Tennessee, Knoxville, tells Nanowerk. "Here, we wanted to develop a way to print it directly on a variety of paper to make a sensor that could respond to touch or specific molecules, such as glucose."
"We also proposed a simplified theoretical model to elucidate the capacitive operating of touch pads, which closely approximated empirical data," notes Hu.
Hu and his collaborators developed a technique that uses a 2D programmed printing machine with postdeposition sintering using a camera flash light to harden the deposited silver nanowire ink.
The researchers point out that the resulting paper-based touchpads produced by direct writing with silver nanowire inks offer several distinct advantages over existing counterparts including:
low-cost and disposable; rapid sintering of nanowires through surface plasmonic excitation, typically requiring 3 flash pulses and less than 20 seconds using a commercial camera flash; ultrathin and ultralight: less than 0.1 mm thickness with printing and inkjet paper substrates and less than 60 mg for a single keypad on printing paper; and flexible and robust: the device responded to touch even when curved, folded and unfolded 15 times, and rolled and unrolled 5,000 times.
The team is now working on printable biosensors and energy devices with paper-based or polymer-based substrates. "We hope that we can integrate micro-sized batteries into a sensor and form a stand-alone microsystem," says Hu.

ref-   © Nanowerk

Based on their special chemical and physical properties, synthetically produced nanomaterials (engineered nanomaterials, ENMs) are currently being used in a wide range of products and applications. The Nanomaterial Databank1 of Nanowerk currently lists nanomaterials composed of 28 different elements as well as of carbon (fullerenes, CNT, graphene), quantum dots consisting of several semi-conductor materials, a large number of simple nanoparticulate compounds (oxides, carbonates, nitrides) and those made up of complex compounds containing several components. On the one hand, the application of nanomaterials promises reduction potentials and sustainability effects for the environment, for example through resource and material savings (see2).
On the other hand, we know very little about the behavior of nanomaterials or about environmental and health risks when these products enter various waste streams at the end of their life cycles. A better understanding of the risks in the so-called End-of-Life-Phase (EOL) calls for considering the different disposal pathways and potential transformation processes that nanomaterials undergo in waste treatment plants. In the disposal phase no consideration is being given to either the special properties of nanomaterials or to potential recovery and re-use.3
There is no special legal framework in place for a separate treatment of nanomaterialcontaining wastes (see4) or the monitoring of the processes. A prerequisite for such a framework would be exact knowledge about the nanomaterials being used, their form (species) and composition, potential transformation processes as well as about amounts and concentrations. Such information, however, is not available, and virtually no studies have been conducted on the EOL phase of products containing nanomaterials. Very little is known about how nanomaterial-containing wastes behave in thermal, biological or mechanical-biological waste treatment plants or in landfills.

Ref- Nanowerk Spotlight

Textile Engineering / 3D-printing with graphene
« on: April 21, 2015, 02:38:42 PM »
The successful implementation of graphene-based devices invariably requires the precise patterning of graphene sheets at both the micrometer and nanometer scale. It appears that 3D-printing techniques are an attractive fabrication route towards three-dimensional graphene structures. In a previous Nanowerk Spotlight we reported on the first 3D printed nanostructures made entirely of graphene.
There are also different methods to build 3D graphene monoliths – for example freeze casting or emulsion templating, etc. – but they are limited to building simple shapes, for example cylinders or cubes.
Using a different approach, researchers have now used flakes of chemically modified graphene – namely graphene oxide GO and its reduced form rGO – together with very small amounts of a responsive polymer (a polymer that changes behavior and conformation when a 'chemical switch' is activated), to formulate water based ink or pastes.
"Our formulations have the flow and physical properties we need for the filament deposition process required in 3D printing: They need to flow through very small nozzles and set immediately after passing through it, retaining the shape and holding the layers on top," Dr. Esther García-Tuñon, a Research Associate at the Centre for Advanced Structural Ceramics at Imperial College London (ICL), tells Nanowerk. "We use this two-dimensional material as building block to create macroscopic 3D structures and a technique called direct ink writing (DIW) also known as direct write assembly (DWA), or Robocasting."
García-Tuñon is first author of a paper in the January 21, 2015 online edition of Advanced Materials ("Printing in Three Dimensions with Graphene") where a team from ICL, the University of Warwick, the University of Bath, and the Universidad de Santiago de Compostela, describe their technique.
This technique is based on the continuous deposition of a filament following a computer design. The 3D structures are built layer by layer from bottom to top.

"Our inks allow printing through nozzles as thin as 100 µm and their rheology could also be tailored for other processing technologies such as extrusion, gel, or tape casting," García-Tuñon points out. "Our goal was to print graphene structures (not composites) using small amounts of additives and water-based systems. In this way it could be easily scaled up in a manufacturing process."
Graphene is very hydrophobic so it is not possible to formulate a water-based ink directly. The researchers therefore used chemically modified graphene – also known as graphene oxide (GO) – instead. GO can be processed in water to build the desired architectures.
Once the structure is made, it is thermally treated in a special atmosphere to recover the properties of graphene.
The mechanical stability of the printed parts may allow the use of additional treatments (e.g., chemical or electrochemical reduction) to further manipulate the properties without compromising the structure.
The team is now working on developing new formulations as well as the development of specific applications for example in flexible electronics and oil adsorption.
"I think there are still many challenges to overcome in both Additive Manufacturing and graphene technologies," notes García-Tuñon. "The buzzword 3D printing is now everywhere; we can find many examples of commercially available 3D printers to make your own Hello Kitty, iPhone cases, and all sort of plastic models. But there is still a long way to go from here to the use of 3D printing for a wide variety of materials in multicomponent and practical devices."
Ref- © Nanowerk

Textile Engineering / On route to self-powered smart suits
« on: April 21, 2015, 02:25:27 PM »
Harvesting energy from tiny mechanical motions such as heartbeats, breathing, footsteps and even blood flow through arteries, is an enticing prospect (read more: "Nanotechnology for self-powered systems"). Another exciting development are nano-sized generators that have piezoelectric properties that allow them to convert into electricity the energy created through mechanical stress, stretches and twists of fabrics.
Such energy-scavenging fabrics could eventually lead to wearable 'smart' clothes that can power integrated electronics and sensors through ordinary body movements.
Researchers have now demonstrated a new type of fully flexible, very robust and wearable triboelectric nanogenerator (WTNG) with high power-generating performance and mechanical robustness.
"We applied a bottom-up nanostructuring approach where we used a silver-coated textile and polydimethylsiloxane (PDMS) nanopatterns based on ZnO nanorod arrays as active triboelectric materials," Sang-Woo Kim, a Professor in the School of Advanced Materials Science & Engineering at Sungkyunkwan University in Korea, tells Nanowerk.
The nanopatterning was achieved by coating PDMS directly over vertical ZnO nanorods grown on the silver-coated textile substrate.
"This nanopatterning promotes the triboelectrification effect by increasing the effective contact area and friction for high electrical output power and very high mechanical robustness by bottom-up nanostructuring between textile and nanostructure," Kim explains.

Reporting their findings in the February 11, 2015 online edition of ACS Nano ("Nanopatterned Textile-Based Wearable Triboelectric Nanogenerator"), Kim, together with collaborators from Sungkyunkwan University and the Australian Institute for Innovative Materials, successfully demonstrated the self-powered operation of LEDs, an LCD and a keyless vehicle entry system only with the output power of their WTNG without any help of external power sources (see Figure 2 below).
This triboelectric power is generated when mechanical stress creates an electrical charge, which is much larger than the power generated from textile-based piezoelectric power generator reported before. This stress can arise through stretching or twisting the textile.
When integrated into clothing, the WTNG relies on its triboelectric property to produce an electrical charge when pressed, and could potentially allow users to power mobile electronics such as smart watches simply by moving or walking around

In previous work, Kim and his team already have reported fully transparent, flexible, and stretchable nanogenerators ("Flexible nano-power with fully transparent and rollable graphene nanogenerators") but they were not robust enough as wearable devices.
By contrast, the researchers tested a four-layer-stacked WTNG over 12000 cycles and found no significant differences in the output voltages they measured.
With the previous devices, the problem was the very weak adhesion between textile and nanostructures which caused mechanical durability issues. In this present work, the researchers overcame these durability problems by bottom-up nanostructuring using ZnO nanorods and PDMS nanopattern coating.
"Triboelectric generation is one of the promising new energy harvesting methods with extremely high output voltage and efficiency, low cost, high versatility and simplicity in structural design and fabrication, stability and robustness, as well as environmental friend," concludes Kim. "Recently, we have been looking to find new materials for huge triboelectrification effects which have never been reported before. Furthermore, there is a need for developing highly efficient power management systems to effectively store electric power generated from triboelectric nanogenerators into textile-based energy storage platforms such as textile batteries or supercapacitors.

Ref- © Nanowerk

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