Tiny Carbon Nanotube-Pores Make BIG Impact


1-Nano Pores 50377Abstract:
A team led by the Lawrence Livermore scientists has created a new kind of ion channel based on short carbon nanotubes, which can be inserted into synthetic bilayers and live cell membranes to form tiny pores that transport water, protons, small ions and DNA.

Tiny carbon nanotube pores make big impact

Livermore, CA | Posted on October 29th, 2014

These carbon nanotube “porins” have significant implications for future health care and bioengineering applications. Nanotube porins eventually could be used to deliver drugs to the body, serve as a foundation of novel biosensors and DNA sequencing applications, and be used as components of synthetic cells.

Researchers have long been interested in developing synthetic analogs of biological membrane channels that could replicate high efficiency and extreme selectivity for transporting ions and molecules that are typically found in natural systems. However, these efforts always involved problems working with synthetics and they never matched the capabilities of biological proteins.

Unlike taking a pill which is absorbed slowly and is delivered to the entire body, carbon nanotubes can pinpoint an exact area to treat without harming the other organs around.

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“Many good and efficient drugs that treat diseases of one organ are quite toxic to another,” said Aleksandr Noy, an LLNL biophysicist who led the study and is the senior author on the paper appearing in the Oct. 30 issue of the journal, Nature. “This is why delivery to a particular part of the body and only releasing it there is much better.”

The Lawrence Livermore team, together with colleagues at the Molecular Foundry at the Lawrence Berkeley National Laboratory, University of California Merced and Berkeley campuses, and University of Basque Country in Spain created a new type of a much more efficient, biocompatible membrane pore channel out of a carbon nanotube (CNT) — a straw-like molecule that consists of a rolled up graphene sheet.

This research showed that despite their structural simplicity, CNT porins display many characteristic behaviors of natural ion channels: they spontaneously insert into the membranes, switch between metastable conductance states, and display characteristic macromolecule-induced blockades. The team also found that, just like in the biological channels, local channel and membrane charges could control the ionic conductance and ion selectivity of the CNT porins.

“We found that these nanopores are a promising biomimetic platform for developing cell interfaces, studying transport in biological channels, and creating biosensors,” Noy said. “We are thinking about CNT porins as a first truly versatile synthetic nanopore that can create a range of applications in biology and materials science.”

“Taken together, our findings establish CNT porins as a promising prototype of a synthetic membrane channel with inherent robustness toward biological and chemical challenges and exceptional biocompatibility that should prove valuable for bionanofluidic and cellular interface applications,” said Jia Geng, a postdoc who is the first co-author of the paper.

Kyunghoon Kim, a postdoc and another co-author, added: “We also expect that our CNT porins could be modified with synthetic ‘gates’ to dramatically alter their selectivity, opening up exciting possibilities for their use in synthetic cells, drug delivery and biosensing.”

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Other LLNL researchers include Ramya Tunuguntla, Kang Rae Cho, Dayannara Munoz and Morris Wang. The team members performed some of the work at the Molecular Foundry DOE user facility as a part of its user project.

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About DOE/Lawrence Livermore National Laboratory
ounded in 1952, Lawrence Livermore National Laboratory (http://www.llnl.gov) provides solutions to our nation’s most important national security challenges through innovative science, engineering and technology. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy’s National Nuclear Security Administration.

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Graphene Solar Panels


1-Graphene solar-panel-array-img_assist-400x301Solar panel electricity systems, also known as solar photovoltaics (PV), capture the sun’s energy (photons) and convert it into electricity. PV cells are made from layers of semiconducting material, and produce an electric field across the layers when exposed to sunlight. When light reaches the cell, some of it is absorbed into the semiconducting material and causes electrons to break loose and flow. This flow of electrons is an electric current, that can be drawn out and used for powering outside devices. This current, along with the cell’s voltage (a result of built-in electric fields), define the power that the solar cell is capable of producing. It is worth mentioning that a PV cell can produce electricity without direct sunlight, but more sunshine equals more electricity.

A module, or panel, is a group of cells connected electrically and packaged together. several panels can also form an array, which can provide more electricity and be used for powering larger instruments and devices.

Different kinds of Solar cells

Solar cells are roughly divided into three categories: Monocrystalline, Polycrystalline and Thin Film. Most of the world’s PVs are based on a variation of silicon. The purity of the silicon, or the more perfectly aligned silicon molecules are, affects how good it will be at converting solar energy. Monocrystalline solar cells (Mono-Si, or single-crystal-Si) go through a process of cutting cylindrical ingots to make silicon wafers, which gives the panels their characteristic look. They have external even coloring that suggests high-purity silicon, thus having the highest efficiency rates (typically 15-20%). They are also space efficient (their efficiency allows them to be small) and live longer than other kinds of solar panels. Alas, they are more expensive than other kinds and tend to be damaged by external dirt or snow.

Polycrystalline silicon (p-Si or mc-Si) solar cells do not go through the abovementioned process, and so are simpler and cost less than Monocrystalline ones. Their typical efficiency is 13-16%, due to lower silicon purity. They are also bigger and take up more space.

Thin-Film solar cells (TFSC), are made by depositing one or several thin layers of photovoltaic material onto a substrate. Different types of TFSCs are categorized by which photovoltaic material is deposited onto the substrate: Amorphous silicon (a-Si), cadmium telluride (CdTe), copper indium gallium selenide (CIS/CIGS), polymer solar panels and organic photovoltaic cells (OPC). Thin-film modules have reached efficiencies of 7-13%. Their mass production is simple, they can be made flexible and are potentially cheaper to manufacture than crystalline-based solar cells. They do, however, take up a lot of space (hampering their use in residential applications) and tend to degrade faster than crystalline solar panels.

Solar power advantages and disadvantages

Solar power is free and infinite, and solar energy use indeed has major advantages. It is an eco-friendly, sustainable way of energy production. Solar energy systems today are also much cheaper than they were 20 years ago, and save money in electricity expenses. In addition, it is a much environmentally cleaner form of energy production that helps reduce global warming and coal pollution. It does not waste water like coal and nuclear power plants and is also considered to be a form of energy that is much safer for use.

Although solar power production is widely considered to be a positive thing, some downsides require mentioning. The initial cost of purchasing and installing solar panels can be substantial, despite widespread government subsidy programs and tax initiatives. Sun exposure is critical and so location plays a significant role in the generation of electricity. Areas that are cloudy or foggy for long periods of time will produce much less electricity. Other commonly argues disadvantages regard insufficiency of produced electricity and reliability issues.

Solar power applications

Common solar energy applications include various residential uses such as solar lighting, heating and ventilation systems. Many small appliances utilize solar energy for operation, like calculators, scales, toys and more. Agriculture and horticulture also employ solar energy for the operation of different aids like water pumps and crop drying machines. The field of transportation has been interested in solar powered vehicles for many years, including cars, planes and boats that are vigorously researched and developed. Solar energy also has various industrial applications, ranging from powering remote locations as well as space and satellite systems, to powering transportation signals, lighthouses, offshore navigation systems and many more.

Solar technologies are vigorously researched, aiming to lower costs and improve existing products as well as integrate PV systems in innovative products like PV-powered curtains, clothes and laptop cases.

Graphene and solar panels

Graphene is made of a single layer of carbon atoms that are bonded together in a repeating pattern of hexagons. It is a 2 dimensional material with amazing characteristics, which grant it the title “wonder material”. It is extremely strong and almost entirely transparent and also astonishingly conductive and flexible. Graphene is made of carbon, which is abundant, and can be a relatively inexpensive material. Graphene has a seemingly endless potential for improving existing products as well as inspiring new ones.

Solar cells require materials that are conductive and allow light to get through, thus benefiting from graphene’s superb conductivity and transparency. Graphene is indeed a great conductor, but it is not very good at collecting the electrical current produced inside the solar cell. Hence, researchers are looking for appropriate ways to modify graphene for this purpose. Graphene Oxide (GO), for example, is less conductive but more transparent and a better charge collector which can be useful for solar panels.

The conductive Indium Tin Oxide (ITO) is used with a non-conductive glass layer as the transparent electrodes in most organic solar panels to achieve these goals, but ITO is rare, brittle and makes solar panels expensive. Many researches focus on graphene as a replacement for ITO in transparent electrodes of OPVs. Others search for ways of utilizing graphene in improving overall performance of photovoltaic devices, mainly OPVs, as well as in electrodes, active layers, interfacial layers and electron acceptors.

Recent research in the field of graphene solar cells

In June 2013, researchers from MIT announced their aim to develop a new solar cell, made from graphene and molybdenum disulfide, which will be thin, light and efficient – up to a 1,000 times more so than silicon based panels. It is hoped to achieve the “ultimate power conversion possible” due to the unique method of stacking several layers of graphene and molybdenum disulfide. In August 2014, researchers from the same university developed a flexible transparent graphene-based electrode for graphene polymer solar cell. They report that this is the most efficient such electrode ever developed.

In March 2014, researchers from the University of Cincinnati discovered that adding even a small amount of graphene flakes to a polymer solar cell can improve the performance of the cell by as much as threefold the conventional non-graphene variant.

In December 2013, researchers from Singapore’s A*STAR institute discovered that graphene outperforms ITO as solar panels transparent electrodes, when stacking four graphene sheets.

Further reading

 

New Solar Power Material Converts 90 Percent of Captured Light into Heat


1-Sunshot PortfolioThumbOctober 29, 2014
A multidisciplinary engineering team developed a new nanoparticle-based material for concentrating solar power plants designed to absorb and convert to heat more than 90 percent of the sunlight it captures. The new material can also withstand temperatures greater than 700 degrees Celsius and survive many years outdoors in spite of exposure to air and humidity.

A multidisciplinary engineering team at the University of California, San Diego developed a new nanoparticle-based material for concentrating solar power plants designed to absorb and convert to heat more than 90 percent of the sunlight it captures. The new material can also withstand temperatures greater than 700 degrees Celsius and survive many years outdoors in spite of exposure to air and humidity. Their work, funded by the U.S. Department of Energy’s SunShot program, was published recently in two separate articles in the journal Nano Energy.

By contrast, current solar absorber material functions at lower temperatures and needs to be overhauled almost every year for high temperature operations.

“We wanted to create a material that absorbs sunlight that doesn’t let any of it escape. We want the black hole of sunlight,” said Sungho Jin, a professor in the department of Mechanical and Aerospace Engineering at UC San Diego Jacobs School of Engineering. Jin, along with professor Zhaowei Liu of the department of Electrical and Computer Engineering, and Mechanical Engineering professor Renkun Chen, developed the Silicon boride-coated nanoshell material. They are all experts in functional materials engineering.

1-UC San Diego New Solar Material 141029095454-large

Graduate student Bryan VanSaders measures how much simulated sunlight a novel material can absorb using a unique set of instruments that takes spectral measurements from visible to infrared. This testing is led by electrical engineering professor Zhaowei Liu.
Credit: David Baillot/UC San Diego Jacobs School of Engineering.

The novel material features a “multiscale” surface created by using particles of many sizes ranging from 10 nanometers to 10 micrometers. The multiscale structures can trap and absorb light which contributes to the material’s high efficiency when operated at higher temperatures.

Concentrating solar power (CSP) is an emerging alternative clean energy market that produces approximately 3.5 gigawatts worth of power at power plants around the globe — enough to power more than 2 million homes, with additional construction in progress to provide as much as 20 gigawatts of power in coming years. One of the technology’s attractions is that it can be used to retrofit existing power plants that use coal or fossil fuels because it uses the same process to generate electricity from steam.

Traditional power plants burn coal or fossil fuels to create heat that evaporates water into steam. The steam turns a giant turbine that generates electricity from spinning magnets and conductor wire coils. CSP power plants create the steam needed to turn the turbine by using sunlight to heat molten salt. The molten salt can also be stored in thermal storage tanks overnight where it can continue to generate steam and electricity, 24 hours a day if desired, a significant advantage over photovoltaic systems that stop producing energy with the sunset.

One of the most common types of CSP systems uses more than 100,000 reflective mirrors to aim sunlight at a tower that has been spray painted with a light absorbing black paint material. The material is designed to maximize sun light absorption and minimize the loss of light that would naturally emit from the surface in the form of infrared radiation.

The UC San Diego team’s combined expertise was used to develop, optimize and characterize a new material for this type of system over the past three years. Researchers included a group of UC San Diego graduate students in materials science and engineering, Justin Taekyoung Kim, Bryan VanSaders, and Jaeyun Moon, who recently joined the faculty of the University of Nevada, Las Vegas. The synthesized nanoshell material is spray-painted in Chen’s lab onto a metal substrate for thermal and mechanical testing. The material’s ability to absorb sunlight is measured in Liu’s optics laboratory using a unique set of instruments that takes spectral measurements from visible light to infrared.

Current CSP plants are shut down about once a year to chip off the degraded sunlight absorbing material and reapply a new coating, which means no power generation while a replacement coating is applied and cured. That is why DOE’s SunShot program challenged and supported UC San Diego research teams to come up with a material with a substantially longer life cycle, in addition to the higher operating temperature for enhanced energy conversion efficiency. The UC San Diego research team is aiming for many years of usage life, a feat they believe they are close to achieving.

Modeled after President Kennedy’s moon landing program that inspired widespread interest in science and space exploration, then-Energy Secretary Steven P. Chu launched the Sunshot Initiative in 2010 with the goal of making solar power cost competitive with other means of producing electricity by 2020.


Story Source:

The above story is based on materials provided by University of California – San Diego. Note: Materials may be edited for content and length.

Nano-Materials for the Next Generation of Electronics and Photovoltaics – Controlling Size


5-materialsforOne of the longstanding problems of working with nanomaterials—substances at the molecular and atomic scale—is controlling their size. When their size changes, their properties also change. This suggests that uniform control over size is critical in order to use them reliably as components in electronics.

Put another way, “if you don’t control size, you will have inhomogeneity in performance,” says Mark Hersam. “You don’t want some of your cell phones to work, and others not.”

Hersam, a professor of materials science engineering, chemistry and medicine at Northwestern University, has developed a method to separate nanomaterials by size, therefore providing a consistency in properties otherwise not available. Moreover, the solution came straight from the life sciences—biochemistry, in fact.

The technique, known as density gradient ultracentrifugation, is a decades-old process used to separate biomolecules. The National Science Foundation (NSF)-funded scientist theorized correctly that he could adapt it to separate carbon nanotubes, rolled sheets of graphene (a single atomic layer of hexagonally bonded carbon atoms), long recognized for their potential applications in computers and tablets, smart phones and other portable devices, photovoltaics, batteries and bioimaging.

The technique has proved so successful that Hersam and his team now hold two dozen pending or issued patents, and in 2007 established their own company, NanoIntegris, jump-started with a $150,000 NSF small business grant. The company has been able to scale up production by 10,000-fold, and currently has 700 customers in 40 countries.

“We now have the capacity to produce ten times the worldwide demand for this material,” Hersam says.

NSF supports Hersam with a $640,000 individual investigator grant awarded in 2010 for five years. Also, he directs Northwestern’s Materials Research Science and Engineering Center (MRSEC), which NSF funds, including support for approximately 30 faculty members/researchers.

Hersam also is a recent recipient of one of this year’s prestigious MacArthur fellowships, a $625,000 no-strings-attached award, popularly known as a “genius” grant. These go to talented individuals who have shown extraordinary originality and dedication in their fields, and are meant to encourage beneficiaries to freely explore their interests without fear of risk-taking.

“This will allow us to take more risks in our research, since there are no ‘milestones’ we have to meet,” he says, referring to a frequent requirement of many funders. “I also have a strong interest in teaching, so I will use the funds to influence as many students as possible.”

The carbon nanotubes separation process, which Hersam developed, begins with a centrifuge tube. Into that, “we load a water based solution and introduce an additive which allows us to tune the buoyant density of the solution itself,” he explains.

“What we create is a gradient in the buoyant density of the aqueous solution, with low density at the top and high density at the bottom,” he continues. “We then load the carbon nanotubes and put it into the centrifuge, which drives the nanotubes through the gradient. The nanotubes move through the gradient until their density matches that of the gradient. The result is that the nanotubes form separated bands in the centrifuge tube by density. Since the density of the nanotube is a function of its diameter, this method allows separation by diameter.”

One property that distinguishes these materials from traditional semiconductors like silicon is that they are mechanically flexible. “Carbon nanotubes are highly resilient,” Hersam says. “That allows us to integrate electronics on flexible substrates, like clothing, shoes, and wrist bands for real time monitoring of biomedical diagnostics and athletic performance. These materials have the right combination of properties to realize wearable electronics.”

He and his colleagues also are working on energy technologies, such as and batteries “that can improve efficiency and reduce the cost of solar cells, and increase the capacity and reduce the charging time of batteries,” he says. “The resulting batteries and solar cells are also mechanically flexible, and thus can be integrated with flexible electronics.”

They likely even will prove waterproof. “It turns out that carbon nanomaterials are hydrophobic, so water will roll right off of them,” he says.

Materials at the nanometer scale now “can realize new properties and combinations of properties that are unprecedented,” he adds. “This will not only improve current technologies, but enable new technologies in the future.”

Explore further: Breakthrough for carbon nanotube solar cells

Researchers Add Graphene Coating to Improve Thermal Conductivity of Plastic


2-researchersiAbstract
We have investigated thermal conductivity of graphene laminate films deposited on polyethylene terephthalate substrates. Two types of graphene laminate were studied, as deposited and compressed, in order to determine the physical parameters affecting the heat conduction the most.

The measurements were performed using the optothermal Raman technique and a set of suspended samples with the graphene laminate thickness from 9 to 44 μm. The thermal conductivity of graphene laminate was found to be in the range from 40 to 90 W/mK at room temperature. It was found unexpectedly that the average size and the alignment of graphene flakes are more important parameters defining the heat conduction than the mass density of the graphene laminate. The thermal conductivity scales up linearly with the average graphene flake size in both uncompressed and compressed laminates. The compressed laminates have higher thermal conductivity for the same average flake size owing to better flake alignment. Coating plastic materials with thin graphene laminate films that have up to 600× higher thermal conductivity than plastics may have important practical implications.

(Phys.org) —A team of engineering and physics researchers with members from the U.S., the U.K. and the Republic of Muldova has found that covering a common type of plastic with a graphene coating can increase its conductivity by up to 600 times. In their paper published in the journal Nano Letters, the team describes their new technique and how the coated materials they’ve created might be used in real world applications.

Plastics are not very good conductors of —they are generally in the 0.15–0.24 W/mK range—which is a good trait when it’s produced as flakes and used as a stuffing inside a winter coat, but not so good when used in electronics that generally need to convey heat away from a source.

Engineers would like to use them in more however, due to their very low cost, light weight and durability. Conversely, is an excellent conductor of heat (in the 2000–5000 W/mK range) along with its other unique properties, though notably a lot of that improvement is lost when applied to a substrate—it’s still much better than plastic though. In this new effort the researchers sought to improve in a plastic by applying graphene to its surface.

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The type of used, PET, is very common—it’s used to make soda bottles and a myriad of other products in a nearly limitless variety of shapes. Graphene for the experiment was grown in sheets just a few microns thick and then applied to a thin sheet of PET. The heat conductance (along the surface) of the resultant material was tested using a non-contact optothermal Raman technique where the researchers found the conductance had been increased by approximately 600 times.

The researchers suggest the graphene coated PET could be used in thermal management applications or thermal lighting or even inside electronic devices to help move heat away from heat generating chips.

The team next plans to work on creating models that have more detail and which are based on multiscale simulations that will shed light on which sorts of real-world applications the coated plastics might best be used in.

Explore further: Researchers combine graphene and copper in hopes of shrinking electronics

New Nanodevice to Improve Cancer Treatment Monitoring


1-nano cancer 81524_relIn less than a minute, a miniature device developed at the University of Montreal can measure a patient’s blood for methotrexate, a commonly used but potentially toxic cancer drug. Just as accurate and ten times less expensive than equipment currently used in hospitals, this nanoscale device has an optical system that can rapidly gauge the optimal dose of methotrexate a patient needs, while minimizing the drug’s adverse effects. The research was led by Jean-François Masson and Joelle Pelletier of the university’s Department of Chemistry.

Methotrexate has been used for many years to treat certain cancers, among other diseases, because of its ability to block the enzyme dihydrofolate reductase (DHFR). This enzyme is active in the synthesis of DNA precursors and thus promotes the proliferation of cancer cells. “While effective, methotrexate is also highly toxic and can damage the healthy cells of patients, hence the importance of closely monitoring the drug’s concentration in the serum of treated individuals to adjust the dosage,” Masson explained.

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Until now, monitoring has been done in hospitals with a device using fluorescent bioassays to measure light polarization produced by a drug sample. “The operation of the current device is based on a cumbersome, expensive platform that requires experienced personnel because of the many samples that need to be manipulated,” Masson said.

Six years ago, Joelle Pelletier, a specialist of the DHFR enzyme, and Jean-François Masson, an expert in biomedical instrument design, investigated how to simplify the measurement of methotrexate concentration in patients.

Gold nanoparticles on the surface of the receptacle change the colour of the light detected by the instrument. The detected colour reflects the exact concentration of the drug in the blood sample. In the course of their research, they developed and manufactured a miniaturized device that works by surface plasmon resonance. Roughly, it measures the concentration of serum (or blood) methotrexate through gold nanoparticles on the surface of a receptacle. In “competing” with methotrexate to block the enzyme, the gold nanoparticles change the colour of the light detected by the instrument. And the colour of the light detected reflects the exact concentration of the drug in the blood sample.

The accuracy of the measurements taken by the new device were compared with those produced by equipment used at the Maisonneuve-Rosemont Hospital in Montreal. “Testing was conclusive: not only were the measurements as accurate, but our device took less than 60 seconds to produce results, compared to 30 minutes for current devices,” Masson said. Moreover, the comparative tests were performed by laboratory technicians who were not experienced with surface plasmon resonance and did not encounter major difficulties in operating the new equipment or obtaining the same conclusive results as Masson and his research team.

IMAGE: As preicse yet 10 times less expensive than current hospital equipment, this little device contains an optical system that enables it to rapidly identify the dose of methotrexate that a…

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In addition to producing results in real time, the device designed by Masson is small and portable and requires little manipulation of samples. “In the near future, we can foresee the device in doctors’ offices or even at the bedside, where patients would receive individualized and optimal doses while minimizing the risk of complications,” Masson said. Another benefit, and a considerable one: “While traditional equipment requires an investment of around $100,000, the new mobile device would likely cost ten times less, around $10,000.”

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About this study:

This research received funding from the National Science and Engineering Research Council (NSERC) of Canada, the Centre for self-assembled chemical structures (CSACS), Fonds québécois de recherche – Nature et technologies (FRQ-NT) and Institut Mérieux.

Swiss Centre for Electronics Makes Near Invisible Solar Modules


1-solarcellA Swiss research and development company said Tuesday it had discovered a way to make white solar modules, which can blend with a building’s “skin” to become virtually invisible.

The Swiss Center for Electronics and Microtechnology (SCEM), a non-profit company for applied research, said it had developed a new technology paving the way to making the world’s first white with no visible cells and connections.

“For decades architects have been asking for a way to customise the colour of solar elements to make them blend into a building’s skin,” it said in a statement.

The problem with the common blue-black solar modules, built to maximise sunlight absorption, is their “visually unaesthetic” appearance, which tends to hamper their acceptance, SCEM said.

“Currently, the market lacks photovoltaic products specifically designed to be integrated into buildings,” it said.

White, the most sought-after colour for its elegance and versatility, is especially tricky because it generally reflects light rather than absorbing it.

To solve the problem, SCEM said it had taken for converting infrared solar light into electricity and combined it with a special filter that “scatters the whole visible spectrum while transmitting infrared light”.

This method, it said, made it possible for crystalline silicon-based solar technologies to be molded into modules that blend seamlessly with building surfaces in any colour, including pure white. “The technology can be applied on top of an existing module or integrated into a new module during assembly, on flat or curved surfaces,” SCEM said.

In addition to use for buildings, it said it expected to see “significant interest” in the technology from the , for use in things like laptops, and from the car industry.

In addition to the aestethic appeal, white have other advantages, SCEM said.

Since the visible, reflected light will not contribute to heat, the solar cells are expected to work at temperatures 20 to 30 degrees Celsius below standard models, it said.

“White PV modules can also contribute to increase energy savings in buildings by keeping inner spaces cooler and reducing air conditioning costs,” it said, noting that several US cities had begun painting roofs white for the same reason.

Explore further: Fully integrating solar power into building design

Partnership to Help Build a New Era of Electronics


Robert Wolkow

U of Alberta physicist Robert Wolkow’s nanotechnology research program got a boost thanks to a $2.7M collaboration with Lockheed Martin and the Alberta government to commercialize the world’s first atomic-scale computing technology.

U of Alberta’s world-leading nanotech research attracts support from an industry giant to usher in atomic-scale computing technology.

U of Alberta 140618-emerald-awards-ualberta-sign-teaser(Edmonton) Support for groundbreaking nanotechnology research led by University of Alberta physics professor Robert Wolkow is the first to be unveiled under an agreement signed earlier this year with the Government of Alberta. Wolkow’s advances in nanomaterials—now part of the U of A spinoff company Quantum Silicon Inc.—is one of three projects to benefit from ties with technology giant Lockheed Martin, made possible through a memorandum of understanding signed with the Alberta government in May 2014. 1-lockheed 1376916720944

This support for the advanced nanotechnologies that have come from Wolkow’s research in the Faculty of Science is the first to be announced Oct. 28 under the MOU. The research program, considered a front-runner in nano-electronics, is pioneering new pathways for atomic-scale technologies that go far beyond the roadmap for ultra-low-power computing devices. “Alberta’s innovation system is helping Alberta companies grow and diversify our economy on the leading edges of technology.

Our innovators and collaborative system attract companies like Lockheed Martin to work with us and move groundbreaking ideas into markets here and worldwide,” said Don Scott, minister of innovation and advanced education. Lorne Babiuk, vice-president (research) at the U of A, notes, “This announcement is an excellent example of what strong partnerships can accomplish. Industry, government and academia are collaborating to advance our province’s innovation agenda.

The work of Professor Wolkow and his team illustrates how basic research and discovery can lead to innovations that benefit society.” Bringing together an international company and a research leader like the U of A creates possibilities for developing new technology and giving students dual literacy in science and in industry, Wolkow says. “I’ve been working in this field for almost 30 years, and today marks the accomplishment of several of my biggest goals as a professor and scientist, including driving new technologies into application and bringing my students into industrial collaborations like this,” notes Wolkow, who is also the chief technology officer of QSi.

Where innovation meets the market In terms of meeting the market, Ken Gordon, CEO of QSi, points out that “taking new solutions to market is deeply complex and requires highly visionary industry leaders to step up, which is what Lockheed Martin has done. Lockheed will provide invaluable insights into the market that will be critical to our success.” Gordon explains, “In order to navigate the complex move from the lab to the market, we convened industry leaders from across North America where the science was exposed to an intense industry review. At the end of that session, the group concluded that the advances Wolkow has made stand to transform the semiconductor industry.”

“Lockheed Martin has been investing in nanomaterial and quantum computing technologies for years. This research on atomic-scale quantum processing with QSi, a Canadian company, has the potential to bring significant new capabilities to Lockheed Martin Canada’s customers, and those of Lockheed Martin globally,” added Charles Bouchard, chief executive of Lockheed Martin Canada.

The $2.7-million collaborative project was created to commercialize the world’s first atomic-scale computing technology. Alberta Innovation and Advanced Education and Lockheed Martin Canada have contributed to the project and secured matching funding from Western Economic Diversification Canada, Quantum Silicon Inc., the National Research Council, the National Institute for Nanotechnology and the U of A. Wolkow also holds a Tier 1 Nanoscale ICT Chair from Alberta Innovates – Technology Futures.

The MOU supports technology commercialization projects in priority areas for Alberta, such as clean technology, advanced materials and nano-structures, advanced water and membrane solutions, environmental sensors and geospatial engineering applications. The agreement also facilitates collaboration between Lockheed Martin, the Alberta Innovates system, Campus Alberta institutions and local companies to pursue solution-oriented technology development and commercialization.

‘Reverse engineering’ materials for more efficient heating and cooling


1-Heating and Cooling 141028114716-largeOctober 28, 2014
Source:
American Institute of Physics (AIP)
 
If you’ve gone for a spin in a luxury car and felt your back being warmed or cooled by a seat-based climate control system, then you’ve likely experienced the benefits of a class of materials called thermoelectrics. Thermoelectric materials convert heat into electricity, and vice versa, and have many advantages over traditional heating and cooling systems. Recently, researchers have observed that the performance of some thermoelectric materials can be improved by combining different solid phases.

f you’ve ever gone for a spin in a luxury car and felt your back being warmed or cooled by a seat-based climate control system, then you’ve likely experienced the benefits of a class of materials called thermoelectrics. Thermoelectric materials convert heat into electricity, and vice versa, and they have many advantages over more traditional heating and cooling systems.

Recently, researchers have observed that the performance of some thermoelectric materials can be improved by combining different solid phases — more than one material intermixed like the clumps of fat and meat in a slice of salami. The observations offer the tantalizing prospect of significantly boosting thermoelectrics’ energy efficiency, but scientists still lack the tools to fully understand how the bulk properties arise out of combinations of solid phases.

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Now a research team based at the California Institute of Technology (Caltech) has developed a new way to analyze the electrical properties of thermoelectrics that have two or more solid phases. The new technique could help researchers better understand multi-phase thermoelectric properties – and offer pointers on how to design new materials to get the best properties.

The team describes their new technique in a paper published in the journal Applied Physics Letters, from AIP Publishing.

An Old Theory Does a 180

Because it’s sometimes difficult to separately manufacture the pure components that make up multi-phase materials, researchers can’t always measure the pure phase properties directly. The Caltech team overcame this challenge by developing a way to calculate the electrical properties of individual phases while only experimenting directly with the composite.

“It’s like you’ve made chocolate chip cookies, and you want to know what the chocolate chips and the batter taste like by themselves, but you can’t, because every bite you take has both chocolate chips and batter,” said Jeff Snyder, a researcher at Caltech who specializes in thermoelectric materials and devices.

To separate the “chips” and “batter” without un-baking the cookie, Snyder and his colleagues turned to a decades old theory, called effective medium theory, and they gave it a new twist.

“Effective medium theory is pretty old,” said Tristan Day, a graduate student in Snyder’s Caltech laboratory and first author on the APL paper. The theory is traditionally used to predict the properties of a bulk composite based on the properties of the individual phases. “What’s new about what we did is we took a composite, and then backed-out the properties of each constituent phase,” said Day.

The key to making the reversal work lies in the different way that each part of a composite thermoelectric material responds to a magnetic field. By measuring certain electrical properties over a range of different magnetic field strengths, the researchers were able to tease apart the influence of the two different phases.

The team tested their method on the widely studied thermoelectric Cu1.97Ag0.03Se, which consists of a main crystal structure of Cu2Se and an impurity phase with the crystal structure of CuAgSe.

Temperature Control of the Future?

Thermoelectric materials are currently used in many niche applications, including air-conditioned car seats, wine coolers, and medical refrigerators used to store temperature-sensitive medicines.

“The definite benefits of using thermoelectrics are that there are no moving parts in the cooling mechanism, and you don’t have to have the same temperature fluctuations typical of a compressor-based refrigerator that turns on every half hour, rattles a bit and then turns off,” said Snyder.

One of the drawbacks of the thermoelectric cooling systems, however, is their energy consumption.

If used in the same manner as a compressor-based cooling system, most commercial thermoelectrics would require approximately 3 times more energy to deliver the same cooling power. Theoretical analysis suggests the energy efficiency of thermoelectrics could be significantly improved if the right material combinations and structures were found, and this is one area where Synder and his colleagues’ new calculation methods may help.

Many of the performance benefits of multi-phase thermoelectrics may come from quantum effects generated by micro- and nano-scale structures. The Caltech researchers’ calculations make classical assumptions, but Snyder notes that discrepancies between the calculations and observed properties could confirm nanoscale effects.

Snyder also points out that while thermo-electrics may be less energy efficient than compressors, their small size and versatility mean they could be used in smarter ways to cut energy consumption. For example, thermoelectric-based heaters or coolers could be placed in strategic areas around a car, such as the seat and steering wheel. The thermoelectric systems would create the feeling of warmth or coolness for the driver without consuming the energy to change the temperature of the entire cabin.

“I don’t know about you, but when I’m uncomfortable in a car it’s because I’m sitting on a hot seat and my backside is hot,” said Snyder. “In principle, 100 watts of cooling on a car seat could replace 1000 watts in the cabin.”

Ultimately, the team would like to use their new knowledge of thermoelectrics to custom design ‘smart’ materials with the right properties for any particular application.

“We have a lot of fun because we think of ourselves as material engineers with the periodic table and microstructures as our playgrounds,” Snyder said.


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The above story is based on materials provided by American Institute of Physics (AIP). Note: Materials may be edited for content and length.

Self-Assembled Membranes Hint at Biomedical Applications


1-SelfAssemblyAPS1Techniques for creating complex nanostructured materials through self-assembly of molecules have grown increasingly sophisticated. But carrying these techniques to the biological realm has been problematic. Recently, scientists from Northwestern University used self-assembly under controlled conditions to create a membrane consisting of layers with distinctly different structures. Now, working at the U.S. Department of Energy’s Advanced Photon Source (APS), the team utilized small-angle x-ray scattering (SAXS) to better determine these structures and study how they form. This new information paves the way for design and synthesis of hierarchical structures with biomedical applications.

Peptide amphiphiles (PA) are chains of amino acids tipped with other molecules so that one end is hydrophilic (mixes well with water) and the other hydrophobic (not fond of water). In aqueous solution, PAs form long, thin nanofibers as the amino acid chains bind to adjacent chains to form β–sheets. The Northwestern University scientists had previously found that when an aqueous solution containing positively-charged PAs was put into contact with an aqueous solution of negatively charged hyaluronic acid (HA—a large biological molecule that occurs in connective and other tissues), a dense, fibrous layer formed within milliseconds, creating a barrier that kept the two solutions from mixing.

1-SelfAssemblyAPS1

More precisely, the researchers found that the fibrous layer prevents aggregated PAs from migrating to the HA side, but allows HA molecules to slowly insinuate themselves through the barrier to the PA side, on a timescale of minutes or longer.

The result was a three-zone membrane structure: a gel-like layer on the HA side, a fibrous mat consisting of PA nanofibers lying in the plane of the interface between the solutions, and a coating of fibers directed perpendicularly away from the interface and formed by electrostatically bound complexes of PA and HA (Image 1).

The team’s interest in these membranes hinged on possible biomedical uses in which the peptide sequence forming the nanofibers would have a chosen biological activity. In one example, they incorporated a heparin-binding sequence to promote angiogenesis (the formation of new blood vessels), so that the membrane might assist with tissue repair. For the three-zone structure to form, the researchers found that the HA solution had to contain heparin in a certain concentration range. Scanning electron microscopy clearly showed linear structure crossing the membrane that formed when heparin was present at 0.5% by weight (Image 2a), in contrast to the more homogeneous appearance of the membrane created in the absence of heparin (Image 2b).

Scanning electron micrographs show the homogeneous membrane that forms in the absence of heparin (A), while in the presence of heparin is a fibrous structure forms transverse to the membrane (B).Scanning electron micrographs show the homogeneous membrane that forms in the absence of heparin (A), while in the presence of heparin is a fibrous structure forms transverse to the membrane (B).The scientists turned to SAXS at the DuPont-Northwestern-Dow Collaborative Access Team beamline 5-ID-D at the Argonne APS, an Office of Science user facility. These studies yield insight into the precise structure of the three-zone membranes and a better understanding of the dynamics of their formation.

The heparin-free membranes produced well-defined Bragg peaks, while the three-zone membranes did not. Moreover, membranes that arose in the presence of smaller heparin concentrations showed larger Bragg peaks than those produced when the heparin concentration was higher, indicating a competition between two structures whose outcome depended on heparin levels.

A time-series of SAXS measurements on a heparin-free experiment showed that the Bragg peaks began to form a few minutes after the two solutions were brought into contact, and reached full strength after about 45 minutes.

Interpreting the SAXS findings in the light of their previous experiments and the known properties of PAs and HA, the scientists explain the differences between the two types of membrane as the result of different kinds of aggregation. In the absence of heparin, the PA and HA come together in nanospherical aggregates that pack together in a cubic arrangement, over a period of some tens of minutes, to form a membrane that generates well-defined Bragg peaks.

When heparin is present, by contrast, it binds strongly with the PA and alters its interaction with AH molecules. In this case, a barrier of nanofibers lying parallel to the solution interface forms immediately, then acts as a diffusion barrier through which HA slowly passes. As it emerges on the other side, it binds to PA to form nanofibers that grow perpendicular to the interface. This ordered nanofiber array produces no Bragg peaks.

The increased understanding and control of these processes derived from this research could make it possible to build bioactive membranes with a variety of structures and purposes.

Electrostatic Control of Structure in Self-Assembled Membranes

Source: Argonne National Laboratory