RATAN-600 radio telescope (credit: nat-geo.ru)

A star system 94 light-years away known as HD 164595 is a possible candidate for intelligent life, based on an announcement by an international team of researchers.

On May 15, 2015, Russian astronomers picked up a radio signal on the RATAN-600 radio telescope in Russia “in the direction of HD164595,” an international group of astronomers stated in a document* now being circulated through contact person Alexander Panov, according to Paul Gilster of Centauri Dreams, who blogged about the data on Saturday, August 27, 2016.

This HD164595 system is known to have one planet, a Neptune-sized world in such a very tight orbit, making it unattractive for life. However, there could be other planets in this system that are still undiscovered, said Seth Shostak, Senior Astronomer at the Seti Institute in a post.

“Raw” record of the signal (purple) together with expected shape of the signal (green) for point-like source in the position of HD 164595. (credit: Bursov et al.)

The observations were not ideal, Shostak notes. They were made with a receiver having a bandwidth of 1 GHz — a billion times wider than the bandwidths traditionally used for SETI, and the strength of the signal was 0.75 Janskys (weak). In addition, the RATAN-600 beam design does not uniquely identify the source direction.

Power required for such a signal would be astronomical, he explains. If broadcast in all directions, the required power is 10²⁰ watts (100 billion billion watts) — hundreds of times more energy than all the sunlight falling on Earth. If aimed at us, assuming an antenna the size of the 1000-foot Arecibo instrument, they would still need to transmit more than a trillion watts.

In addition, the signal was received at 11Ghz (2.7 cm wavelength), in a part of the radio spectrum used by the military, so the signal may be due to terrestrial radio-frequency interference, or to gravitational lensing from a more distant source.

Shostak said the SETI Institute swung the Allen Telescope Array (ATA) in the direction of HD 164595 beginning Sunday evening, August 28. No detections reported yet.

The radio signal and the ensuring follow-up investigations will be discussed at the 67th International Astronautical Congress in Guadalajara, Mexico on September 27th.

* “The presentation [was] forwarded to me by Claudio Maccone [the chair of the International Academy of Astronautics Permanent SETI Committee], from which I learn that the team behind the detection was led by N.N. Bursov and included L.N. Filippova, V.V. Filippov, L.M. Gindilis, A.D. Panov, E.S. Starikov, J. Wilson, as well as Claudio Maccone,” said Gilster. The detection was made in Zelenchukskaya, in the Karachay–Cherkess Republic of Russia.

In this series, a 3-D printed multimaterial shape-memory minigripper, consisting of shape-memory hinges and adaptive touching tips, grasps a cap screw. The material is designed to close when the temperature of the surrounding air is raised to specific temperature or higher (credit: Qi (Kevin) Ge)

Engineers from MIT and Singapore University of Technology and Design (SUTD) are 3D-printing structures based on shape-memory polymers that “remember” and spring back to their original shapes when heated to a certain temperature “sweet spot” — even after being stretched, twisted, and bent at extreme angles.

That makes them useful for applications ranging from soft actuators that turn solar panels toward the sun to tiny drug capsules that open upon early signs of infection. Other applications include biomedical devices, deployable aerospace structures, and shape-changing photovoltaic solar cells.

For some structures, the researchers were able to 3D-print micrometer-scale features as small as the diameter of a human hair — dimensions at least ten times smaller than with other printable shape-memory materials, but with materials that can be stretched 10 times larger than those printed by commercial 3-D printers.

The team’s results were published earlier this month in the online open-access journal Scientific Reports.

“We ultimately want to use body temperature as a trigger,” says Nicholas X. Fang, associate professor of mechanical engineering at MIT. “If we can design these polymers properly, we may be able to form a drug delivery device that will only release medicine at the sign of a fever.”

”Fang and others have been exploring the use of soft, active materials as reliable, pliable tools. These new and emerging materials, which include shape-memory polymers, can stretch and deform dramatically in response to environmental stimuli such as heat, light, and electricity — properties that researchers have been investigating for use in biomedical devices, soft robotics, wearable sensors, and artificial muscles.

Shape-memory polymers can switch between two states — a harder, low-temperature, amorphous state, and a soft, high-temperature, rubbery state. The bent and stretched shapes can be “frozen” at room temperature, and when heated the materials will “remember” and snap back to their original sturdy form.

“If you’re able to make it to much smaller dimensions, these materials can actually respond very quickly, within seconds,” Fang says. “For example, a flower can release pollen in milliseconds. It can only do that because its actuation mechanisms are at the micron scale.”

Printing with light

Workflow for the process of fabricating a multimaterial structure based on microstereolithography (credit: Qi Ge et al./Scientific Reports)

To print shape-memory structures with even finer details, Fang and his colleagues used a 3-D printing process they have pioneered, called “microstereolithography” (PμSL), in which they use light from a projector to print patterns on successive layers of resin. It uses a family of photo-curable methacrylate-based copolymer networks, designing the constituents and compositions to exhibit desired thermomechanical behavior.*

The researchers first create a model of a structure using computer-aided design (CAD) software, then divide the model into hundreds of slices, each of which they send through the projector as a bitmap — an image file format that represents each layer as an arrangement of very fine pixels. The projector then shines light in the pattern of the bitmap, onto a liquid resin, or polymer solution, etching the pattern into the resin, which then solidifies.

Fang found that the structures could be stretched to three times their original length without breaking. “Because we’re using our own printers that offer much smaller pixel size, we’re seeing much faster response, on the order of seconds,” Fang says. “If we can push to even smaller dimensions, we may also be able to push their response time, to milliseconds.”

“This is a very advanced 3-D printing method compared to traditional nozzle or ink-jet based printers,” says Shaochen Chen, professor of nano-engineering at the University of California at San Diego, who was not involved in the research. “The method’s main advantages are faster printing and better structural integrity.”

Soft grip

To demonstrate a simple application for the shape-memory structures, Fang and his colleagues printed a small, rubbery, claw-like gripper. They attached a thin handle to the base of the gripper, then stretched the gripper’s claws open.

“The grippers are a nice example of how manipulation can be done with soft materials,” Fang says. “We showed that it is possible to pick up a small bolt, and also even fish eggs and soft tofu. That type of soft grip is probably very unique and beneficial.”

Going forward, he hopes to find combinations of polymers to make shape-memory materials that react to slightly lower temperatures, approaching the range of human body temperatures, to design soft, active, controllable drug delivery capsules. He says the material may also be printed as soft, responsive hinges to help solar panels track the sun.

Scientists at Rutgers University, SUTD, and Georgia Institute of Technology were also involved in the research, which is supported in part by the SUTD Digital Manufacturing and Design Center (DManD) and the SUTD-MIT joint postdoctoral program.

* “We’re printing with light, layer by layer,” Fang says. “It’s almost like how dentists form replicas of teeth and fill cavities, except that we’re doing it with high-resolution lenses that come from the semiconductor industry, which give us intricate parts, with dimensions comparable to the diameter of a human hair.”

The researchers looked through the scientific literature to identify an ideal mix of polymers to create a shape-memory material on which to print their light patterns. They picked two polymers, one composed of long-chain polymers, or spaghetti-like strands, and the other resembling more of a stiff scaffold. When mixed together and cured, the material can be stretched and twisted dramatically without breaking.

What’s more, the material can bounce back to its original printed form, within a specific temperature range — in this case, between 40 and 180 degrees Celsius (104 to 356 degrees Fahrenheit).

Abstract of Multimaterial 4D Printing with Tailorable Shape Memory Polymers

We present a new 4D printing approach that can create high resolution (up to a few microns), multimaterial shape memory polymer (SMP) architectures. The approach is based on high resolution projection microstereolithography (PμSL) and uses a family of photo-curable methacrylate based copolymer networks. We designed the constituents and compositions to exhibit desired thermomechanical behavior (including rubbery modulus, glass transition temperature and failure strain which is more than 300% and larger than any existing printable materials) to enable controlled shape memory behavior. We used a high resolution, high contrast digital micro display to ensure high resolution of photo-curing methacrylate based SMPs that requires higher exposure energy than more common acrylate based polymers. An automated material exchange process enables the manufacture of 3D composite architectures from multiple photo-curable SMPs. In order to understand the behavior of the 3D composite microarchitectures, we carry out high fidelity computational simulations of their complex nonlinear, time-dependent behavior and study important design considerations including local deformation, shape fixity and free recovery rate. Simulations are in good agreement with experiments for a series of single and multimaterial components and can be used to facilitate the design of SMP 3D structures.

A biochemical system for reducing epileptic activity (experimentally generated chemically) in mice hippocampus brain tissue. The miniature “neural pixel” device (bottom) sensed the epileptic attack and then delivered the natural calming neurotransmitter GABA via PEDOT:PSS electrodes, which also  recorded the subsequent electrophysiological activity to confirm effectiveness. (credit: Amanda Jonsson et al./PNAS)

Researchers at Linköping University in Sweden and in France have developed a “neural pixel” device that when implanted in a mouse hippocampus brain slice detects the initial signal of an epileptic attack and also locally administers the exact dose of the natural neurotransmitter GABA needed to stop the attack.

The researchers used a conducting polymer called poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) for electrodes. It has ten times better conductivity than gold, platinum, and iridium electrodes.  A tiny organic electronic ion pump* was used to pump the GABA neurotransmitter through a selective membrane, enabling high spatiotemporal delivery resolution (tiny and works fast) without requiring liquid flow (which is hard to control).

The idea is to have local, real-time measurement and precision delivery directly to specific neurons, which could pave the way in the future to closed-loop, fully automatic, miniature therapeutic devices. Combining electronic detection and release in the same electrode is a major advance, according to the researchers.

The development offers an alternative to drugs taken orally, which may be toxic outside the brain, may not cross the blood−brain barrier, or may have deleterious side effects when they penetrate the brain’s “healthy” regions, affecting physiological functions such as memory and learning. It also opens up a range of opportunities in basic neuroscience.

The research results have been published in the journal Proceedings of the National Academy of Sciences (PNAS).

* The implantable ion pump was developed at Linköping University’s Laboratory for Organic Electronics and announcedin 2015. It was used initially to deliver exact dosages of painkiller GABA to the exact location where the pain signals reach the spinal cord for further transmission to the brain, and could be in clinical use in five to ten years, the researchers say.

The neural sensor for the initial signal of an epileptic attack was developed by the LiU researchers’ collaborators at the École Nationale Supérieure des Mines in Gardanne, France. The mouse experiments were performed at Aix-Marseille University. The entire device is manufactured from conductive, biocompatible plastic.

The Swedish part of the research was funded by Vinnova, the Swedish Research Council, and the Knut and Alice Wallenberg Foundation. The work took place at the OBOE center, under the leadership of Asst. Prof. Daniel Simon and Professor Magnus Berggren.

Abstract of Bioelectronic neural pixel: Chemical stimulation and electrical sensing at the same site

Local control of neuronal activity is central to many therapeutic strategies aiming to treat neurological disorders. Arguably, the best solution would make use of endogenous highly localized and specialized regulatory mechanisms of neuronal activity, and an ideal therapeutic technology should sense activity and deliver endogenous molecules at the same site for the most efficient feedback regulation. Here, we address this challenge with an organic electronic multifunctional device that is capable of chemical stimulation and electrical sensing at the same site, at the single-cell scale. Conducting polymer electrodes recorded epileptiform discharges induced in mouse hippocampal preparation. The inhibitory neurotransmitter, γ-aminobutyric acid (GABA), was then actively delivered through the recording electrodes via organic electronic ion pump technology. GABA delivery stopped epileptiform activity, recorded simultaneously and colocally. This multifunctional “neural pixel” creates a range of opportunities, including implantable therapeutic devices with automated feedback, where locally recorded signals regulate local release of specific therapeutic agents.

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Protein-shelled structures called gas vesicles, illustrated here, can be engineered with Lego-like proteins to improve ultrasound methods. The gas vesicles can help detect specific cell types and create multicolor images. (credit: Barth van Rossum for Caltech)

The next step in ultrasound imaging will let doctors view specific cells and molecules deeper in the body, such as those associated with tumors or bacteria in our gut.

A new study from Caltech outlines how protein engineering techniques might help achieve this milestone. The researchers engineered protein-shelled nanostructures called gas vesicles (which reflect sound waves) to exhibit new properties useful for ultrasound technologies. In the future, these gas vesicles could be administered to a patient to visualize tissues of interest.

The modified gas vesicles were shown to give off more distinct signals (making them easier to image), target specific cell types, and help create color ultrasound images.

“It’s somewhat like engineering with molecular Legos,” says assistant professor of chemical engineering and Heritage Principal Investigator Mikhail Shapiro, who is the senior author of a new paper about the research published in this month’s issue of the journal ACS Nano and featured on the journal’s cover. “We can swap different protein ‘pieces’ on the surface of gas vesicles to alter their targeting properties and to visualize multiple molecules in different colors.”

“Gas vehicle” proteins reflect sound waves

Genetic engineering of gas vesicles — genetically encoded protein nanostructures isolated from buoyant photosynthetic microbes — results in nanostructures with new mechanical, acoustic, surface, and functional properties to enable harmonic, multiplexed, and multimodal ultrasound imaging as well as cell-specific molecular targeting. (credit: Anupama Lakshmanan et al./ACS Nano)

In 2014, Shapiro first discovered the potential use of gas vesicles in ultrasound imaging. These gas-filled structures are naturally occurring in water-dwelling single-celled organisms, such as Anabaena flos-aquae, a species of cyanobacteria that forms filamentous clumps of multicell chains.

The gas vesicles help the organisms control how much they float and thus their exposure to sunlight at the water’s surface. Shapiro realized that the vesicles would readily reflect sound waves during ultrasound imaging, and ultimately demonstrated this using mice.

Genetic engineering a type of protein called GvpC (gas vesicle protein C) can be used to modify the properties of acoustic gas-vesicle nanostructures. (credit: Anupama Lakshmanan et al./ACS Nano)

In the latest research, Shapiro and his team set out to give the gas vesicles new properties by engineering gas vesicle protein C, or GvpC, a protein naturally found on the surface of vesicles that gives them mechanical strength and prevents them from collapsing. The protein can be engineered to have different sizes, with longer versions of the protein producing stronger and stiffer nanostructures.

In one experiment, the scientists removed the strengthening protein from gas vesicles and then administered the engineered vesicles to mice and performed ultrasound imaging. Compared to normal vesicles, the modified vesicles vibrated more in response to sound waves, and thus resonated with harmonic frequencies.

Harmonics are created when sound waves bounce around, for instance in a violin, and form new waves with doubled and tripled frequencies. Harmonics are not readily created in natural tissues, making the vesicles stand out in ultrasound images.

In another set of experiments, the researchers demonstrated how the gas vesicles could be made to target certain tissues in the body. They genetically engineered the vesicles to display various cellular targets, such as an amino acid sequence that recognizes proteins called integrins that are overproduced in tumor cells.

Multicolor ultrasound images

The team also showed how multicolor ultrasound images might be created. Conventional ultrasound images appear black and white. Shapiro’s group created an approach for imaging three different types of gas vesicles as separate “colors” based on their differential ability to resist collapse under pressure. The vesicles themselves do not appear in different colors, but they can be assigned colors based on their different properties.

To demonstrate this, the team made three different versions of the vesicles with varying strengths of the GvpC protein. They then increased the ultrasound pressures, causing the variant populations to successively collapse one by one.

As each population collapsed, the overall ultrasound signal decreased in proportion to the amount of that variant in the sample, and this signal change was then mapped to a specific color. In the future, if each variant population targeted a specific cell type, researchers would be able to visualize the cells in multiple colors.

“You might be able to see tumor cells versus the immune cells attacking the tumor, and thus monitor the progress of a medical treatment,” says Shapiro.

The ACS Nano paper, entitled “Molecular Engineering Of Acoustic Protein Nanostructures,” was funded by the National Institutes of Health, the Defense Advanced Research Projects Agency, the Heritage Research Institute for the Advancement of Medicine and Science at Caltech, and the Burroughs Wellcome Fund.

Abstract of Molecular Engineering of Acoustic Protein Nanostructures

Ultrasound is among the most widely used biomedical imaging modalities, but has limited ability to image specific molecular targets due to the lack of suitable nanoscale contrast agents. Gas vesicles—genetically encoded protein nanostructures isolated from buoyant photosynthetic microbes—have recently been identified as nanoscale reporters for ultrasound. Their unique physical properties give gas vesicles significant advantages over conventional microbubble contrast agents, including nanoscale dimensions and inherent physical stability. Furthermore, as a genetically encoded material, gas vesicles present the possibility that the nanoscale mechanical, acoustic, and targeting properties of an imaging agent can be engineered at the level of its constituent proteins. Here, we demonstrate that genetic engineering of gas vesicles results in nanostructures with new mechanical, acoustic, surface, and functional properties to enable harmonic, multiplexed, and multimodal ultrasound imaging as well as cell-specific molecular targeting. These results establish a biomolecular platform for the engineering of acoustic nanomaterials.