Study explores nanoscale structure of thin films

The world’s newest and brightest synchrotron light source—the National Synchrotron Light Source II (NSLS-II) at the U.S. Department of Energy’s Brookhaven National Laboratory—has produced one of the first publications resulting from work done during the facility's science commissioning phase. Published July 7 in the online edition of the (a recently launched journal of the International Union of Crystallography), the paper discusses a new way to apply a widely used local-structure analysis tool—known as atomic pair distribution function (PDF) analysis—to x-ray scattering data from thin films, quickly yielding high-quality information on the films' atomic structure. The work creates new avenues for studies of nanocrystalline thin films. This work shows that NSLS-II—a DOE Office of Science User Facility with ultra-bright, ultra-concentrated x-ray beams—is already proving to be a game-changer in studies of thin films, which play a vital role in a large number of technologies, including computer chips and solar cells. Simon Billinge Simon Billinge, author on the paper and a physicist with a joint position at Brookhaven National Laboratory and Columbia University's School of Engineering and Applied Science. Thin film challenges In applications and during experiments, thin films (defined as having thicknesses from just a few to more than 1000 nanometers, or billionths of a meter) are deposited onto a thick base, called a substrate, often made of crystalline wafers of silicon, silicon dioxide, or aluminum oxide. It is extremely difficult to study the structure of materials in this geometry because of the small amount of film material and large amount of substrate. To minimize the scattering of x-rays off the substrate, which tends to obscure the data from the tiny volume of sample, thin film x-ray studies are done using grazing incidence (GI) x-ray experiments. In GI studies, the x-ray beam grazes the surface of the film such that it reflects off the substrate, allowing the beam to illuminate as much of the film as possible while minimizing penetration through the film into the substrate. However, the small angle of incidence makes GI studies notoriously difficult to carry out and introduces serious complexities in data analysis. “Grazing-incidence diffraction experiments are tricky for crystalline materials, and have never successfully been done to obtain PDFs from films,” said one of the paper's authors, Simon Billinge, a physicist with a joint position at Brookhaven and Columbia University's School of Engineering and Applied Science. “The experiments are too painstaking and the data analysis is extremely challenging.” Studying the ‘atomic neighborhood’ PDF provides local atomic structural information – that is, data for neighborhoods of atoms – by yielding the distances between all pairs of atoms in the sample. These distances appear as peaks in the data. In recent years, PDF has become a standard technique in structural studies of complex materials and can be used for samples that are bulk or nanoscale, amorphous or crystalline. The approach that Billinge and his colleagues devised leverages the high fluxes of photons coming from NSLS-II, which, together with novel data reduction methods recently developed in his group, creates data suitable for PDF analysis from a thin film. Essentially, it turns the standard GI experiment on its head: the beam is simply sent through the film from the back to the front. Eric Dooryhee, the lead scientist for the NSLS-II X-Ray Powder Diffraction (XPD) beamline, where the work was done, explained, “The first group of NSLS-II beamlines is now successfully transitioning from technical commissioning, which began back in the fall of 2014 when we first produced x-ray light, towards science commissioning, where we benchmark and test the beamline capabilities on real samples. Extracting the thin film's tiny signal from the substrate's large signal in this normal-incidence geometry is extremely technically difficult. Nonetheless, I told Simon that XPD should be up to the challenge.” Preview of future breakthroughs The group tested thin-film PDF (which they call tfPDF) with both crystalline and amorphous thin films, each about 360 nm thick. The collaboration includes the groups of Bo Iversen at Aarhus University in Denmark and Dave Johnson from the University of Oregon, who prepared the thin films. The first sample studied was an amorphous iron-antimony film on an amorphous borosilicate substrate mounted perpendicular to the x-ray beam. In order to isolate the contribution from the film, the substrate contribution was first determined by measuring the scattering pattern from a clean substrate. The signal from the film is barely visible in the raw data on top of the large substrate contribution, but could be clearly extracted during data processing. This allowed for a reliable, low-noise PDF that can be modeled successfully to yield the quantitative atomic structure of the film. The data led to high-quality PDFs for both amorphous and crystalline films—confirmed by comparison to control samples in a standard PDF setup. Based on the success of these first measurements, the Billinge group and the XPD team are now planning future experiments to watch the films crystallize in real time, in the beam. “The discovery that we can get PDFs from samples in thin-film geometry so readily will revolutionize this area of science,” said Kirsten Jensen, a postdoctoral researcher in Billinge’s group at Columbia. “The experiments don’t take any specialized equipment or expertise beyond the beamline setup at XPD and are quick, opening the way to time-resolved in-situ studies of changes in film structure under processing as well as spatially resolved studies of nanostructured films in place.” Added Billinge, “This is an exciting new result by itself, but it only gives us a glimpse of the possibilities that NSLS-II will present as the power ramps up over the next few years. This is the tip of the iceberg of what will be possible when NSLS-II is operating at full power.”
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Nanotechnology developed to help treat heart attack and stroke

Australian researchers funded by the National Heart Foundation are a step closer to a safer and more effective way to treat heart attack and stroke via nanotechnology. The research jointly lead by Professor Christoph Hagemeyer, Head of the Vascular Biotechnology Laboratory at Baker IDI Heart and Diabetes Institute and Professor Frank Caruso, an ARC Australian Laureate Fellow in the Department of Chemical and Biomolecular Engineering at the University of Melbourne, was published today in ("Multifunctional Thrombin-Activatable Polymer Capsules for Specific Targeting to Activated Platelets"). clot-busting treatment Professor Hagemeyer said this latest step offers a revolutionary difference between the current treatments for blood clots and what might be possible in the future. This life saving treatment could be administered by paramedics in emergency situations without the need for specialised equipment as is currently the case. “We’ve created a nanocapsule that contains a clot-busting drug. The drug-loaded nanocapsule is coated with an antibody that specifically targets activated platelets, the cells that form blood clots,” Professor Hagemeyer said. “Once located at the site of the blood clot, thrombin (a molecule at the centre of the clotting process) breaks open the outer layer of the nanocapsule, releasing the clot-busting drug. We are effectively hijacking the blood clotting system to initiate the removal of the blockage in the blood vessel,” he said. Professor Frank Caruso from the Melbourne School of Engineering said the targeted drug with its novel delivery method can potentially offer a safer alternative with fewer side effects for people suffering a heart attack or stroke. “Up to 55,000 Australians experience a heart attack or suffer a stroke every year.” “About half of the people who need a clot-busting drug can’t use the current treatments because the risk of serious bleeding is too high,” he said.
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Nanoparticles in bottle plastic doubles shelf life of pasteurized fresh milk

Agrindus, an agribusiness company located in São Carlos, São Paulo state, Brazil, has increased the shelf life of grade A pasteurized fresh whole milk from seven to 15 days. plastic milk bottle
This feat was achieved by incorporating silver-based microparticles with bactericidal, antimicrobial and self-sterilizing properties into the rigid plastic bottles used as packaging for the milk.

The technology was developed by Nanox, also located in São Carlos. Supported by FAPESP's Innovative Research in Small Business (PIPE) program, the nanotechnology company is a spinoff from the Center for Research and Development of Functional Materials (CDFM), one of the Research, Innovation and Dissemination Centers (RIDCs) supported by São Paulo Research Foundation (FAPESP).

"We already knew use of our antimicrobial and bactericidal material in rigid or flexible plastic food packaging improves conservation and extends shelf life. So we decided to test it in the polyethylene used to bottle grade A fresh milk in Brazil. The result was that we more than doubled the product's shelf life solely by adding the material to the packaging, without mixing any additives with the milk", said the Nanox CEO, Luiz Pagotto Simões.

According to Simões, the microparticles are included as a powder in the polyethylene preform that is used to make plastic bottles by blow or injection molding. The microparticles are inert, so there is no risk of their detaching from the packaging and coming into contact with the milk. Tests of the material's effectiveness in extending the shelf life of fresh milk were performed for a year by Agrindus, Nanox and independent laboratories. "Only after shelf life extension had been certified did we decide to bring the material to market," Simões said. In addition to Agrindus, the material is also being tested by two other dairies that distribute fresh milk in plastic bottles in São Paulo and Minas Gerais and by dairies in the Brazilian southern region that sell fresh milk in flexible plastic packaging. "In milk bags, the material is capable of extending shelf life from four to ten days," he said. Nanox plans to market the product in Europe and the United States, where much larger volumes of fresh milk are consumed than in Brazil. The kind of milk most consumed in Brazil is ultra-high temperature (UHT), or "long life" milk, which is sterilized at temperatures ranging from 130°C to 150°C for two to four seconds to kill most of the bacterial spores. Unopened UHT milk has a shelf life of up to four months at room temperature. Whole milk, known as grade A in Brazil, is pasteurized at much lower temperatures by the farmer and requires refrigeration. "Doubling the shelf life of whole milk translates into significant benefits in terms of logistics, storage, quality and food safety," Simões said. Countless applications The silver-based microparticles developed by Nanox are currently being used in several other products other than packaging for fresh milk, including plastic utensils, PVC film for wrapping food, toilet seats, shoe insoles, hair dryers and flatirons, paints, resins, and ceramics, as well as coatings for medical and dental instruments such as grippers, drills and scalpels. But the company's largest markets today are makers of rugs, carpets, and white goods, such as refrigerators, drinking fountains and air conditioners. "We've supplied several products to white goods manufacturers since 2007," Simões said. "This material is shipped to the leading players in the market." Nanox currently exports the product to 12 countries via local distributors in Chile, China, Colombia, Italy, Mexico and Japan, among others. The company now wants to enter the United States, having won approval in 2013 from the Food & Drug Administration (FDA) to market the bactericidal material for use in food packaging. "We've applied for clearance by the EPA [the Environmental Protection Agency] so that we can sell to a larger proportion of the US market," Simões said. Neither Brazil nor the US has clear legislation on the use of particles at the nanometer scale [a billionth of a meter] in products that involve contact with food, so the company uses nanotechnology processes that result in silver-based particles at the micrometer scale [a millionth of a meter], he said. The core of the technology consists of coating ceramic particles made of silica with silver nanoparticles. The silver nanoparticles bond with the ceramic matrix to form a micrometre scale composite with bactericidal properties. "The combination of silver particles with a ceramic matrix produces synergistic effects. Silver has bactericidal properties, and while silica doesn't, it boosts those of the silver and helps control the release of silver particles to kill bacteria," he said.
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