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Molecular Switch for Controlling Color

A collaboration of researchers from Kumamoto, Yamaguchi, and Osaka Universities in Japan have discovered a new method of drastically changing the color and fluorescence of a particular compound using only oxygen (O2) and hydrogen (H2) gases. The fully reversible reaction is environmentally friendly since it produces only water as a byproduct. Rather than using electrical or photo energy, the discovery uses energy from the gases themselves, which is expected to become a future trend, to switch the color and fluorescence properties. The technique could be used as a detection sensor for hydrogen or oxygen gases as well as for property controls of organic semiconductors and organic light emitting diodes (OLEDs). Polyaromatic compounds (PACs) are widely used in fluorescent materials, semiconductor materials, organic EL devices, and organic solar-cell devices. The research performed at Kumamoto University focused on using energy from gases"We tried to determine the most attractive compounds that could freely and dramatically change the optical properties of the PAC with a redox reaction," said Associate Professor Hayato Ishikawa from Kumamoto University. "Specifically, we introduced an orthoquinone moiety to the PAC that possessed the most ideal switching properties under a redox reaction with hydrogen and oxygen gases." To determine the candidates with the best switching properties, researchers screened several orthoquinone-containing aromatic compounds in a computational study. The ideal molecules clearly showed switching between fluorescence emission and quenching, and between a colored and colorless state. Picene-13, 14-dione was nominated as the most promising candidate from the computational analysis. The researchers then developed an original protocol to efficiently synthesize the compound from commercially available petroleum raw materials. The key steps for the synthesis were the transition metal-catalyzed coupling reaction and the ring construction reaction by an organocatalyst. This synthetic methodology is also applicable to the synthesis of various other similar compounds or derivatives. A palladium nanoparticle catalyst was added to the synthesized picene-13, 14-dione and then H2 gas was bubbled into the solution. As predicted by the computational study, a dramatic change in color and fluorescence of the solution was observed; its color and fluorescence changed from yellow to colorless, and from non-fluorescent to blue fluorescent respectively. The subsequent reverse oxidation proceeded smoothly when H2 gas was exchanged for O2 gas, and the solution reverted back to its original state. "When we performed a detailed analysis, it was revealed that the resultant changes in color and fluorescence were caused by two different molecular states. The prediction of these states, and our ideas about this phenomenon, were strongly supported by both the computational analysis and the experimental results," said Ishikawa. "This molecular switching technology of an aromatic compound using an orthoquinone moiety is a new insight that appears to have been reported first by our research team."

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Intelligent Machine Tool Prototype

A research group led by Professor Shirase Keiichi of the Kobe University Graduate School of Engineering has developed a prototype machine tool that can manufacture metal components and operates like a 3D printer. This development could speed up the manufacture of custom-made products such as dental implants and artificial bones, potentially shortening production times and reducing costs. The machine tool prototype is a product of Kobe University's ongoing research into intelligent machine tools. This is one of three Kobe University projects in the category of innovative design and manufacturing technologies selected for the Strategic Innovation Promotion Program (SIP), a project headed by the Japanese Cabinet Office's Council for Science, Technology and Innovation. Currently most machine tools for metal cutting follow instructions from a program that is manually prepared in advance. However, in addition to the huge amount of labor required to create each program, this method has potential issues, as the machines cannot make adjustments to the machining process or respond to unforeseen problems. Metal components can also be shaped using metal 3D printers, but this too has disadvantages including the expense of the the metal powder used as a raw material. The prototype created by Professor Shirase's team marks a shift from providing machine tools with instructions to entrusting machine tools with the machining operation. If you prepare a 3D model and a material model of the component, the machine tool itself will determine the optimum machining process using a database of machining information and cutting conditions. This development could potentially pave the way for intelligent manufacturing systems, reduced costs, and faster production times.

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Discovery to Boost Efficiency of Cells

Scientists from the Department of Energy's Lawrence Berkeley National Laboratory have discovered a possible secret to dramatically boosting the efficiency of perovskite solar cells hidden in the nanoscale peaks and valleys of the crystalline material. Solar cells made from compounds that have the crystal structure of the mineral perovskite have captured scientists' imaginations. They're inexpensive and easy to fabricate, like organic solar cells. Even more intriguing, the efficiency at which perovskite solar cells convert photons to electricity has increased more rapidly than any other material to date, starting at 3 percent in 2009, when researchers first began exploring the material's photovoltaic capabilities, to 22 percent today. This is in the ballpark of the efficiency of silicon solar cells. Now, as reported online in the journal Nature Energy, a team of scientists from the Molecular Foundry and the Joint Center for Artificial Photosynthesis, both at Berkeley Lab, found a surprising characteristic of a perovskite solar cell that could be exploited for even higher efficiencies, possibly up to 31 percent. Using photoconductive atomic force microscopy, the scientists mapped two properties on the active layer of the solar cell that relate to its photovoltaic efficiency. The maps revealed a bumpy surface composed of grains about 200 nanometers in length, and each grain has multi-angled facets like the faces of a gemstone. Unexpectedly, the scientists discovered a huge difference in energy conversion efficiency between facets on individual grains. They found poorly performing facets adjacent to highly efficient facets, with some facets approaching the material's theoretical energy conversion limit of 31 percent. The scientists say these top-performing facets could hold the secret to highly efficient solar cells, although more research is needed. "If the material can be synthesized so that only very efficient facets develop, then we could see a big jump in the efficiency of perovskite solar cells, possibly approaching 31 percent," says Sibel Leblebici, a postdoctoral researcher at the Molecular Foundry. Leblebici works in the lab of Alexander Weber-Bargioni, who is a corresponding author of the paper that describes this research. Ian Sharp, also a corresponding author, is a Berkeley Lab scientist at the Joint Center for Artificial Photosynthesis. Other Berkeley Lab scientists who contributed include Linn Leppert, Francesca Toma, and Jeff Neaton, the director of the Molecular Foundry.

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Lens Sees Smaller Than Wavelength of Light

Curved lenses, like those in cameras or telescopes, are stacked in order to reduce distortions and resolve a clear image. That's why high-power microscopes are so big and telephoto lenses so long. While lens technology has come a long way, it is still difficult to make a compact and thin lens (rub a finger over the back of a cellphone and you'll get a sense of how difficult). But what if you could replace those stacks with a single flat, or planar, lens? Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have demonstrated the first planar lens that works with high efficiency within the visible spectrum of light, covering the whole range of colors from red to blue. The lens can resolve nanoscale features separated by distances smaller than the wavelength of light. It uses an ultrathin array of tiny waveguides, known as a metasurface, which bends light as it passes through, similar to a curved lens. "This technology is potentially revolutionary because it works in the visible spectrum, which means it has the capacity to replace lenses in all kinds of devices, from microscopes to camera, to displays and cell phones," said Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering and senior author of the paper. "In the near future, metalenses will be manufactured on a large scale at a small fraction of the cost of conventional lenses, using the foundries that mass produce microprocessors and memory chips." In order to focus red, blue, and green light, the team needed a material that wouldn't absorb or scatter light, said Rob Devlin, a graduate student and co-author of the paper. "We needed a material that would strongly confine light with a high refractive index. And in order for this technology to be scalable, we needed a material already used in industry." The team used titanium dioxide, a ubiquitous material found in everything from paint to sunscreen, to create the nanoscale array of smooth and high-aspect ratio nanostructures that form the heart of the metalens. "We wanted to design a single planar lens with a high numerical aperture, meaning it can focus light into a spot smaller than the wavelength," said Mohammadreza Khorasaninejad, a postdoctoral fellow and first author of the paper. "The more tightly you can focus light, the smaller your focal spot can be, which potentially enhances the resolution of the image." The team designed the array to resolve a structure smaller than a wavelength of light, around 400 nanometers across. At these scales, the metalens could provide better focus than a state-of-the art commercial lens.

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A Soft Control Architecture: Breakthrough in Hard Real-Time Design for Complex Systems

How to cut costs, improve quality, and differentiate your products with a software-based approach to machine automation OEMs have long relied on expensive, cumbersome hardware like FPGAs and DSPs for precision motion control. But new advances in software-based machine automation are changing that paradigm, with huge potential benefits.

Posted in: White Papers, Electronics & Computers, Manufacturing & Prototyping, Motion Control, Machinery & Automation, Robotics, Semiconductors & ICs, Software

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5 Real-Time, Ethernet-Based Fieldbuses Compared

Ethernet-based fieldbus standards have changed the game for machine builders. But with so many protocols competing to be most valuable and viable, how should you decide which to use?

Posted in: White Papers, Electronics & Computers, Motion Control, Machinery & Automation, Robotics, Software

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Software vs Hardware Machine Control: Cost and Performance Compared

OEMs traditionally used DSP-based hardware, plugged into a PC, for motion control. But new software-based solutions have challenged this approach, claiming equal or better performance at lower cost.

Posted in: White Papers, Manufacturing & Prototyping, Motion Control, Machinery & Automation, Robotics

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