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Category: materials

3D printing has opened up a completely new range of possibilities. One example is the production of novel turbine buckets. However, the 3D printing process often induces internal stress in the components, which can, in the worst case, lead to cracks. Now a research team has succeeded in using neutrons from the Technical University of Munich (TUM) research neutron source for non-destructive detection of this internal stress—a key achievement for the improvement of the production processes.

Gas turbine buckets have to withstand extreme conditions: Under and at high temperatures they are exposed to tremendous centrifugal forces. In order to further maximize energy yields, the buckets have to hold up to temperatures which are actually higher than the melting point of the material. This is made possible using hollow turbine buckets which are air-cooled from the inside.

These turbine buckets can be made using , an additive manufacturing technology: Here, the starter material in powder form is built up layer by layer by selective melting with a laser. Following the example of avian bones, intricate lattice structures inside the hollow turbine buckets provide the part with the necessary stability.

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**A lobster’s underbelly is lined with a thin, translucent membrane that is both stretchy and surprisingly tough.** This marine under-armor, as MIT engineers reported in 2019, is made from the toughest known hydrogel in nature, which also happens to be highly flexible. This combination of strength and stretch helps shield a lobster as it scrabbles across the seafloor, while also allowing it to flex back and forth to swim.

A lobster’s underbelly is lined with a thin, translucent membrane that is both stretchy and surprisingly tough. This marine under-armor, as MIT engineers reported in 2019, is made from the toughest known hydrogel in nature, which also happens to be highly flexible. This combination of strength and stretch helps shield a lobster as it scrabbles across the seafloor, while also allowing it to flex back and forth to swim.

Now a separate MIT team has fabricated a hydrogel-based material that mimics the structure of the lobster’s underbelly. The researchers ran the material through a battery of stretch and impact tests, and showed that, similar to the lobster underbelly, the is remarkably “fatigue-resistant,” able to withstand repeated stretches and strains without tearing.

If the fabrication process could be significantly scaled up, materials made from nanofibrous hydrogels could be used to make stretchy and strong replacement tissues such as artificial tendons and ligaments.

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Imagine a foldable smartphone or a rollable tablet device that is powerful, reliable and, perhaps most importantly, affordable.

New research directed by Wake Forest University scientists and published today in the journal Nature Communications has led to a method for both pinpointing and eliminating the sources of instability in the materials and devices used to create such applications.

“In this work, we introduced a strategy that provides a reliable tool for identifying with high accuracy the environmental and operational device degradation pathways and subsequently eliminating the main sources of instabilities to achieve stable devices,” said lead author Hamna Iqbal, a who worked closely with Professor of Physics Oana Jurchescu on the research.

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The second-generation of their implantable scaffold takes the shape of an ice cube tray, and can hold three times as many photoreceptor cells — 300000 of them in all — and features cylindrical holes on the underside so these cells can connect with the patient’s retinal tissue as they mature. It is made from a biocompatible material called poly(glycerol-sebacate) that offers the necessary mechanical strength, but is safely metabolized by the body after it serves its purpose.

One of the main causes of vision loss in adults is deteriorative disorders of the retina, like macular degeneration, that are characterized by the death of the eye’s photoreceptor cells. Scientists are therefore focusing a lot of attention on coming up with ways to regenerate these cells, and a team at the University of Wisconsin-Madison (UW-Madison) has engineered a novel type of scaffold that could give these efforts a boost, by improving the precision with which replacement photoreceptor cells can be delivered into the eye.

Way back in 2012, we looked at research in which UW-Madison scientists demonstrated how pluripotent stem cells could be used to grow retinal tissue in the lab. This tissue featured many of the hallmarks of real retinal tissue, including photoreceptor cells, and raised the prospect of harnessing this technique to grow replacement tissue in place within a damaged or diseased eye to restore vision.

“While it was a breakthrough to be able to make the spare parts – these photoreceptors – it’s still necessary to get them to the right spot so they can effectively reconstruct the retina,” says professor of ophthalmology and visual sciences David Gamm. “So, we started thinking, ‘How can we deliver these cells in a more intelligent way?’ That’s when we reached out to our world-class engineers at UW–Madison.”

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We are made of stardust, the saying goes, and a pair of studies including University of Michigan research finds that may be more true than we previously thought.

The first study, led by U-M researcher Jie (Jackie) Li and published in Science Advances, finds that most of the carbon on Earth was likely delivered from the interstellar medium, the material that exists in space between stars in a galaxy. This likely happened well after the protoplanetary disk, the cloud of dust and gas that circled our young sun and contained the building blocks of the planets, formed and warmed up.

Carbon was also likely sequestered into solids within one million years of the sun’s birth — which means that carbon, the backbone of life on earth, survived an interstellar journey to our planet.

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A team of researchers working at Barcelona Institute of Science and Technology has developed a skeletal-muscle-based, biohybrid soft robot that can swim faster than other skeletal-muscle-based biobots. In their paper published in the journal Science Robotics, the group describes building and testing their soft robot.

As scientists continue to improve the abilities of soft robots, they have turned to such as animal tissue. To date, most efforts in this area have involved the use of skeletal or cardiac muscles—each have their strengths and weaknesses. Skeletal-muscle-based biobots have, for example, suffered from lack of mobility and strength. In this new effort, the researchers in Spain have developed a new design for a tinyskeletal-muscle-based that overcomes both issues and is therefore able to swim faster than others of its kind.

To make their biobot, the researchers used a simulation to create a spring-based spine for a swimming creature shaped like an eel. The simulation allowed the researchers to optimize its shape. They then 3D printed the skeleton (which was made of a polymer called PDMS) and used it as a scaffold for growing skeletal muscles. The finished was approximately 260 micrometers long—its shape allowed for propulsion in just one direction. The biobot moves when given ; the charge incites the muscle to contract, which compresses the skeletal spring inside. When the stimulation is removed, the energy in the spring is released, pushing the biobot forward.

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Oxygen diatomic molecules have lone-pair electrons and magnetic moments. A high-pressure phase called epsilon oxygen is considered stable in a wide pressure range. This material exhibits the transition to metal at ∼100 GPa (1000, 000× atmospheric pressure). The change in the electronic structure involved in the transition under pressure is difficult to measure using conventional methods. In this study, the electronic structures of oxygen have been successfully measured with oxygen K-edge X-ray Raman scattering spectroscopy. We found a change in the spectra related to the metallization of oxygen. Another change in the electronic structure was also observed at ∼40 GPa. This is likely related to the semimetallic transition.

Electronic structures of dense solid oxygen have been investigated up to 140 GPa with oxygen K-edge X-ray Raman scattering spectroscopy with the help of ab initio calculations based on density functional theory with semilocal metageneralized gradient approximation and nonlocal van der Waals density functionals. The present study demonstrates that the transition energies (Pi*, Sigma*, and the continuum) increase with compression, and the slopes of the pressure dependences then change at 94 GPa. The change in the slopes indicates that the electronic structure changes at the metallic transition. The change in the Pi* and Sigma* bands implies metallic characteristics of dense solid oxygen not only in the crystal a–b plane but also parallel to the c axis. The pressure evolution of the spectra also changes at ∼40 GPa.

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Despite artificial intelligence and robotics adapting to many other areas of life and the work force, construction has long remained dominated by humans in neon caps and vests. Now, the robotics company Baubot has developed a Printstones robot, which they hope to supplement human construction workers onsite.

Baubot manufacturers built this with the capacity to transport heavy loads, lay bricks and even sand sheetrock. So far, the Austria-based company has come out with two robots – a smaller prototype with a 40-inch arm and a larger robot with an 82-inch arm.

Users can switch out the type of digits at the end of each arm depending on what type of task they need the bot to perform. For example, an arm tip has the ability to cut, drill, sand and also use a suction feature to elevate heavy rocks into the proper location. Both types of robot can transport over one ton of material.

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Encoding information into light, and transmitting it through optical fibers lies at the core of optical communications. With an incredibly low loss of 0.2 dB/km, optical fibers made from silica have laid the foundations of today’s global telecommunication networks and our information society.

Such ultralow optical loss is equally essential for integrated photonics, which enable the synthesis, processing and detection of optical signals using on-chip waveguides. Today, a number of innovative technologies are based on integrated photonics, including semiconductor lasers, modulators, and photodetectors, and are used extensively in data centers, communications, sensing and computing.

Integrated photonic chips are usually made from silicon that is abundant and has good optical properties. But silicon can’t do everything we need in integrated photonics, so new material platforms have emerged. One of these is silicon nitride (Si3N4), whose exceptionally low optical loss (orders of magnitude lower than that of silicon), has made it the material of choice for applications for which low loss is critical, such as narrow-linewidth lasers, photonic delay lines, and nonlinear photonics.

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Over the past decade or so, the semimetal graphene has attracted substantial interest among electronics engineers due to its many advantageous qualities and characteristics. In fact, its high electron mobility, flexibility and stability make it particularly desirable for the development of next-generation electronics.

Despite its advantageous properties, large-area has a zero bandgap (i.e., the energy range in solid materials at which no electronic states can exist). This means that in graphene cannot be completely shut off. This characteristic makes it unsuitable for the development of many electronic devices.

Researchers at Tsinghua University in China recently devised a design strategy that could be used to attain a larger bandgap in graphene. This strategy, introduced in a paper published in Nature Electronics, entails the use of an electric field to control conductor-to-insulator transitions in microscale graphene.

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