Graphene is a one-atom-thick sheet of carbon. On the two-dimensional scale, the material is stronger than steel, but because graphene is so thin, it is still subject to ripping and tearing.

Rebar graphene is the nanoscale analog of rebar (reinforcement bars) in concrete, in which embedded steel bars enhance the material’s strength and durability. Rebar graphene, developed by the Rice lab of chemist James Tour in 2014, uses carbon nanotubes for reinforcement.

In a new study in the American Chemical Society journal ACS Nano, Rice materials scientist Jun Lou, graduate student and lead author Emily Hacopian and collaborators, including Tour, stress-tested rebar graphene and found that nanotube rebar diverted and bridged cracks that would otherwise propagate in unreinforced graphene.

The experiments showed that nanotubes help graphene stay stretchy and also reduce the effects of cracks. That could be useful not only for flexible electronics but also electrically active wearables or other devices where stress tolerance, flexibility, transparency and mechanical stability are desired, Lou said.

Both the lab’s mechanical tests and molecular dynamics simulations by collaborators at Brown University revealed the material’s toughness.

Graphene’s excellent conductivity makes it a strong candidate for devices, but its brittle nature is a downside, Lou said. His lab reported two years ago that graphene is only as strong as its weakest link. Those tests showed the strength of pristine graphene to be “substantially lower” than its reported intrinsic strength. In a later study, the lab found molybdenum diselenide, another two-dimensional material of interest to researchers, is also brittle.

Tour approached Lou and his group to carry out similar tests on rebar graphene, made by spin-coating single-walled nanotubes onto a copper substrate and growing graphene atop them via chemical vapor deposition.

To stress-test rebar graphene, Hacopian, Yang and colleagues had to pull it to pieces and measure the force that was applied. Through trial and error, the lab developed a way to cut microscopic pieces of the material and mount it on a testbed for use with scanning electron and transmission electron microscopes.

“We couldn’t use glue, so we had to understand the intermolecular forces between the material and our testing devices,” Hacopian said. “With materials this fragile, it’s really difficult.”

Rebar didn’t keep graphene from ultimate failure, but the nanotubes slowed the process by forcing cracks to zig and zag as they propagated. When the force was too weak to completely break the graphene, nanotubes effectively bridged cracks and in some cases preserved the material’s conductivity.

In earlier tests, Lou’s lab showed graphene has a native fracture toughness of 4 megapascals. In contrast, rebar graphene has an average toughness of 10.7 megapascals, he said.

Simulations by study co-author Huajian Gao and his team at Brown confirmed results from the physical experiments. Gao’s team found the same effects in simulations with orderly rows of rebar in graphene as those measured in the physical samples with rebar pointing every which way.

“The simulations are important because they let us see the process on a time scale that isn’t available to us with microscopy techniques, which only give us snapshots,” Lou said. “The Brown team really helped us understand what’s happening behind the numbers.”

He said the rebar graphene results are a first step toward the characterization of many new materials. “We hope this opens a direction people can pursue to engineer 2D material features for applications,” Lou said.

Hacopian, Yingchao Yang of the University of Maine and Bo Ni of Brown University are co-lead authors of the paper. Co-authors are Yilun Li, Hua Guo of Rice, Xing Li of Rice and Zhengzhou University and Qing Chen of Peking University. Lou is a professor of materials science and nanoengineering at Rice. Tour is the T.T. and W.F. Chao Chair in Chemistry and a professor of computer science and of materials science and nanoengineering Rice. Gao is the Walter H. Annenberg Professor of Engineering at Brown.

The research was supported by the Welch Foundation, the Air Force Office of Scientific Research’s Multidisciplinary University Research Institute, the Department of Energy Office of Basic Energy Sciences, the National Natural Science Foundation of China and the National Science Foundation.

“Life-saving bone marrow transplants have been the common practice for decades, but this doesn’t work for everybody,” says Stowers Institute Investigator Linheng Li, Ph.D., study lead who is also co-leader of the cancer biology program at the University of Kansas Cancer Center and an affiliate professor of pathology and laboratory medicine at the University of Kansas School of Medicine.

Only 30 percent of patients have a bone marrow donor match available in their families, according to the US Department of Health and Human Services. More than 170,000 people in the US are expected to be diagnosed in 2018 with a blood cancer (leukemia, lymphoma, or myeloma) according to the American Cancer Society.

Adult stem cells from umbilical cords are more likely to be a match for more people because there are fewer compatibility requirements than for a bone marrow transplant. But adult patients need two cords’ worth of blood per treatment, and there aren’t enough cord units available for everyone who needs the treatment. “If we can expand cord adult stem cells, that could potentially decrease the number of cords needed per treatment. That’s a huge advantage,” says Li.

In the study, published online July 31, 2018, in Cell Research, researchers zeroed in on a protein that affects multiple targets and pathways involved in hematopoietic stem cell self-renewal, a broader approach than other studies that focus on a single target or pathway in the process. The protein, called Ythdf2, recognizes a particular type of modification on a group of mRNAs encoding key transcription factors for hematopoietic stem cell self-renewal and promotes the decay of these mRNAs within cells.

When the team knocked out Ythdf2 function in a mouse model or knocked down Ythdf2 function in hUCB cells, they observed increased expression of these transcription factors and expansion of hematopoietic stem cells, which are the major type of adult stem cells in hUCB. They observed that impairing Ythdf2 function did not alter the types of cells that were subsequently produced, nor did it lead to increased blood cell malignancies. In addition, the knock down treatment isn’t permanent, thereby allowing Ythdf2’s function to be restored after transplantation.

“Our approach of targeting Ythdf2 function using an RNA-based technique also helped avoid more persistent DNA-related changes such as mutations in epigenetic regulators,” says Zhenrui Li, PhD, a predoctoral researcher at the University of Kansas Medical Center who is performing thesis research in the Linheng Li Lab and first author of the study.

Those kinds of genetic mutations could lead to the re-genesis of leukemia or cancer, Zhenrui Li explains. Since the Ythdf2 protein is present in different kinds of adult stem cells, targeting it and how it affects hematopoietic stem cells seemed a safer approach and, if it worked, broadly applicable.

Linheng Li believes that this approach could potentially be applied to other types of adult stem cells, which may lead to increasing the amount of adult stem cells available for treating patients. This may also be complementary to the approach of haploidentical adult stem cell transplants, which involve donors from a close but still mismatched family member. These patients typically require immune suppression treatment to suppress graft versus host disease.

“This work represents a path forward by demonstrating the ability to reliably expand adult stem cells from umbilical cord blood in the laboratory without terminally differentiating the cells into more mature and relatively short-lived blood cells,” says Joseph McGuirk, MD, professor of medicine and medical director of blood and marrow transplant at the University of Kansas Health System, who was not directly involved with the study. “These findings represent a major advance in the field and have significant potential to improve the outcomes of thousands of children and adults who undergo umbilical cord blood transplantation every year.”

Weyl semimetals require broken inversion crystal symmetry or time-reversal symmetry (via magnetic order or an applied magnetic field). So far, no intrinsic magnetic Weyl semimetals with Weyl nodes close to the Fermi energy were realized. In the recent study, scientists from the Max Planck Institute for Chemical Physics of Solids in Dresden, in collaboration with the Technische Universita?t Dresden, scientists from Beijing, Princeton, Oxford, and others found evidence for Weyl physics in the magnetic Shandites Co₃Sn₂S₂. The family of Shandite crystals contain transition metals on a quasi 2-dimensional Kagome lattice that can give rise to magnetism. One of the most interesting is Co₃Sn₂S₂ which has the highest magnetic ordering temperature within this family and in which the magnetic moments on the Co atoms are aligned in a direction perpendicular to the Kagome plane.

The observation of the quantum anomalous Hall effect at room temperature would allow for novel computing technologies including quantum computing. To realize this possibility, our strategy is (i) to search for quasi two-dimensional magnetic materials with topological band structures and (ii) to synthesis these materials as monolayers or very thin films. However, so far no magnetic materials are known, which could lead to higher temperature quantum anomalous Hall effect. In order to obtain large Hall angles, namely the ratio of the Hall to the electrical conductivities, two conditions must be satisfied: firstly a large Hall conductivity and secondly a small number of carriers. These conditions are met in Weyl semi-metals where the Weyl nodes are close in energy to the Fermi energy.

We have found that Co₃Sn₂S₂ displays a giant anomalous Hall effect and a giant hall angle at temperatures of up to 150 K suggestive of a Weyl semimetal. Subsequent band structure calculations indeed show the presence of Weyl nodes close to the Fermi energy. Moreover, magnetotransport measurements give evidence for a chiral anomaly that is a clear signature of a Weyl semimetal. Our work provides a clear path to the observation of a quantum anomalous hall effect at room temperature by exploring families of magnetic Weyl semimetals.

This study, for the first time, realizes the giant anomalous Hall effects by using a magnetic Weyl semimetal, which establishes the magnetic Weyl semimetal candidate Co₃Sn₂S₂ as a key class of materials for fundamental research and applications connecting the topological physics and spintronics. With a long-range out-of-plane ferromagnetism on the Kagomé-lattice model for the platform of quantum topological states, we further expect that this material is an excellent candidate for observation of the quantum anomalous Hall state in the two-dimensional limit.

The research at the Max Planck Institute for Chemical Physics of Solids (MPI CPfS) in Dresden aims to discover and understand new materials with unusual properties.

In close cooperation, chemists and physicists (including chemists working on synthesis, experimentalists and theoreticians) use the most modern tools and methods to examine how the chemical composition and arrangement of atoms, as well as external forces, affect the magnetic, electronic and chemical properties of the compounds.

New quantum materials, physical phenomena and materials for energy conversion are the result of this interdisciplinary collaboration.

The MPI CPfS is part of the Max Planck Society and was founded in 1995 in Dresden. It consists of around 280 employees, of which about 180 are scientists, including 70 doctoral students.

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“I was on a trip with my parents in Central America and we were served fried ants,” she says. “I remember being so grossed out initially, but when I put the ant in my mouth, I was really surprised because it tasted like food — and it was good!”

Today, Stull, a recent doctoral graduate of the University of Wisconsin-Madison Nelson Institute for Environmental Studies, is the lead author of a new pilot clinical trial published in the journal Scientific Reports that looks at what eating crickets does to the human microbiome.

It shows that consuming crickets can help support the growth of beneficial gut bacteria and that eating crickets is not only safe at high doses but may also reduce inflammation in the body.

“There is a lot of interest right now in edible insects,” Stull says. “It’s gaining traction in Europe and in the U.S. as a sustainable, environmentally friendly protein source compared to traditional livestock.”

More than 2 billion people around the world regularly consume insects, which are also a good source of protein, vitamins, minerals and healthy fats. The research team was interested in documenting for the first time via clinical trial the health effects of eating them.

“This study is important because insects represent a novel component in Western diets and their health effects in human populations haven’t really been studied,” says co-corresponding author Tiffany Weir, a professor of food science and human nutrition at Colorado State University. “With what we now know about the gut microbiota and its relationship to human health, it’s important to establish how a novel food might affect gut microbial populations. We found that cricket consumption may actually offer benefits beyond nutrition.”

Raising insects for protein not only helps protect the environment, but also offers a more healthful option than meat in many wealthy countries with high-meat diets, says co-author Jonathan Patz, director of the UW-Madison Global Health Institute, where Stull will begin a postdoctoral research position in the fall.

Crickets, like other insects, contain fibers, such as chitin, that are different from the dietary fiber found in foods like fruits and vegetables. Fiber serves as a microbial food source and some fiber types promote the growth of beneficial bacteria, also known as probiotics. The small trial probed whether insect fibers might influence the bacteria found in the gastrointestinal tract.

For two weeks, 20 healthy men and women between the ages of 18 and 48 ate either a control breakfast or a breakfast containing 25 grams of powdered cricket meal made into muffins and shakes. Each participant then ate a normal diet for a two-week “washout period.” For the following two weeks, those who started on the cricket diet consumed a control breakfast and those who started on the control diet consumed a cricket breakfast.

Every participant served as their own control for the study and the researchers were blinded with respect to which diet each participant was on at any given time.

The researchers collected blood samples, stool samples and answers to gastrointestinal questionnaires immediately before the study began, immediately following the first two-week diet period and immediately after the second two-week diet period.

Participants’ blood samples were tested for a host of health measures, like blood glucose and enzymes associated with liver function, and also for levels of a protein associated with inflammation. The fecal samples were tested for the byproducts of microbial metabolism in the human gut, inflammatory chemicals associated with the gastrointestinal tract, and the overall makeup of the microbial communities present in the stools.

Participants reported no significant gastrointestinal changes or side effects and the researchers found no evidence of changes to overall microbial composition or changes to gut inflammation. They did see an increase in a metabolic enzyme associated with gut health, and a decrease in an inflammatory protein in the blood called TNF-alpha, which has been linked to other measures of well-being, like depression and cancer.

Additionally, the team saw an increase in the abundance of beneficial gut bacteria like Bifidobacterium animalis, a strain that has been linked to improved gastrointestinal function and other measures of health in studies of a commercially available strain called BB-12.

But, the researchers say, more and larger studies are needed to replicate these findings and determine what components of crickets may contribute to improved gut health. “This very small study shows that this is something worth looking at in the future when promoting insects as a sustainable food source,” says Stull.

Stull is co-founder of an award-winning startup and research collaboration called MIGHTi, the Mission to Improve Global Health Through Insects. In the future, MIGHTi hopes to provide home-use insect-farming kits to communities that already consume insects, including many in southern Africa. Insects require far less water to farm than traditional livestock and can help improve food security in impoverished communities while providing economic opportunities to women.

“Most of the insects consumed around the world are wild-harvested where they are and when they are available,” says Stull, who has eaten insects — including caterpillars, cicadas, grasshoppers and beetle larvae — all over the world. “People love flying termites in Zambia, which come out only once or twice a year and are really good; they taste like popcorn and are a crunchy, oily snack.”

She hopes to promote insects as a more mainstream food in the United States, and though the industry is currently small, the rise of edible insect producers and companies using insects in their food products may make this possible.

“Food is very tied to culture, and 20 or 30 years ago, no one in the U.S. was eating sushi because we thought it was disgusting, but now you can get it at a gas station in Nebraska,” she says.

The study was funded by a multistate Hatch project (W3122: Beneficial and Adverse Effects of Natural Chemicals on Human Heath and Food Safety), the Karen Morris-Fine New Investigator Success Fund, the Climate Quest competition, and the Clinical and Translational Science Award program of the NIH National Center for Advancing Translational Sciences (UL1TR000427). Entomo Farms donated a portion of the cricket powder used in the study.

“Today, our country’s dreams of greater achievements in space are within our grasp,” said NASA Administrator Jim Bridenstine. “This accomplished group of American astronauts, flying on new spacecraft developed by our commercial partners Boeing and SpaceX, will launch a new era of human spaceflight. Today’s announcement advances our great American vision and strengthens the nation’s leadership in space.”

The agency assigned nine astronauts to crew the first test flight and mission of both Boeing’s CST-100 Starliner and SpaceX’s Crew Dragon. NASA has worked closely with the companies throughout design, development and testing to ensure the systems meet NASA’s safety and performance requirements.

“The men and women we assign to these first flights are at the forefront of this exciting new time for human spaceflight,” said Mark Geyer, director of NASA’s Johnson Space Center in Houston. “It will be thrilling to see our astronauts lift off from American soil, and we can’t wait to see them aboard the International Space Station.”

Starliner Test Flight Astronauts

Eric Boe was born in Miami and grew up in Atlanta. He came to NASA from the Air Force, where he was a fighter pilot and test pilot and rose to the rank of colonel. He was selected as an astronaut in 2000 and piloted space shuttle Endeavour for the STS-126 mission and Discovery on its final flight, STS-133.

Christopher Ferguson is a native of Philadelphia. He is a retired Navy captain, who piloted space shuttle Atlantis for STS-115, and commanded shuttle Endeavour on STS-126 and Atlantis for the final flight of the Space Shuttle Program, STS-135. He retired from NASA in 2011 and has been an integral part of Boeing’s CST-100 Starliner program.

Nicole Aunapu Mann is a California native and a lieutenant colonel in the Marine Corps. She is an F/A-18 test pilot with more than 2,500 flight hours in more than 25 aircraft. Mann was selected as an astronaut in 2013. This will be her first trip to space.

Boeing’s Starliner will launch aboard a United Launch Alliance (ULA) Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida.

Crew Dragon Test Flight Astronauts

Robert Behnken is from St. Ann, Missouri. He has a doctorate in engineering and is a flight test engineer and colonel in the Air Force. He joined the astronaut corps in 2000 and flew aboard space shuttle Endeavour twice, for the STS-123 and STS-130 missions, during which he performed six spacewalks totaling more than 37 hours.

Douglas Hurley calls Apalachin, New York, his hometown. He was a test pilot and colonel in the Marine Corps before coming to NASA in 2000 to become an astronaut. He piloted space shuttle Endeavor for STS-127 and Atlantis for STS-135, the final space shuttle mission.

SpaceX’s Crew Dragon will launch aboard a SpaceX Falcon 9 rocket from Launch Complex 39A at Kennedy Space Center in Florida.

After each company successfully completes its crewed test flight, NASA will begin the final process of certifying that spacecraft and systems for regular crew missions to the space station. The agency has contracted six missions, with as many as four astronauts per mission, for each company.

Starliner First Mission Astronauts

Josh Cassada grew up in White Bear Lake, Minnesota. He is a Navy commander and test pilot with more than 3,500 flight hours in more than 40 aircraft. He was selected as an astronaut in 2013. This will be his first spaceflight.

Sunita Williams was born in Euclid, Ohio, but considers Needham, Massachusetts, her hometown. Williams came to NASA from the Navy, where she was a test pilot and rose to the rank of captain before retiring. Since her selection as an astronaut in 1998, she has spent 322 days aboard the International Space Station for Expeditions 14/15 and Expeditions 32/33, commanded the space station and performed seven spacewalks.

Crew Dragon First Mission Astronauts

Victor Glover is from Pomona, California. He is a Navy commander, aviator and test pilot with almost 3,000 hours flying more than 40 different aircraft. He made 400 carrier landings and flew 24 combat missions. He was selected as part of the 2013 astronaut candidate class, and this will be his first spaceflight.

Michael Hopkins was born in Lebanon, Missouri, and grew up on a farm near Richland, Missouri. He is a colonel in the Air Force, where he was a flight test engineer before being selected as a NASA astronaut in 2009. He has spent 166 days on the International Space Station for Expeditions 37/38, and conducted two spacewalks.

Additional crew members will be assigned by NASA’s international partners at a later date.

NASA’s continuous presence on the space station for almost 18 years has enabled technology demonstrations and research in biology and biotechnology, Earth and space science, human health, physical sciences. This research has led to dramatic improvements in technology, infrastructure and medicine, and thousands of spinoff technologies that have improved quality of life here on Earth.

The new spaceflight capability provided by Boeing and SpaceX will allow NASA to maintain a crew of seven astronauts on the space station, thereby maximizing scientific research that leads to breakthroughs and also aids in understanding and mitigating the challenges of long-duration spaceflight.

NASA’s Commercial Crew Program is facilitating the development of a U.S. commercial crew space transportation capability with the goal of achieving safe, reliable and cost-effective access to and from the International Space Station and low-Earth orbit. The public-private partnerships fostered by the program will stimulate growth in a robust commercial space industry and spark life-changing innovations for future generations.

Learn more about NASA’s Commercial Crew Program at: https://www.nasa.gov/commercialcrew